diff --git a/accessible/src/base/nsCoreUtils.cpp b/accessible/src/base/nsCoreUtils.cpp
index f9b4353c1e2d..90f011803664 100644
--- a/accessible/src/base/nsCoreUtils.cpp
+++ b/accessible/src/base/nsCoreUtils.cpp
@@ -513,7 +513,7 @@ nsCoreUtils::GetUIntAttr(nsIContent *aContent, nsIAtom *aAttr, PRInt32 *aUInt)
   nsAutoString value;
   aContent->GetAttr(kNameSpaceID_None, aAttr, value);
   if (!value.IsEmpty()) {
-    PRInt32 error = NS_OK;
+    nsresult error = NS_OK;
     PRInt32 integer = value.ToInteger(&error);
     if (NS_SUCCEEDED(error) && integer > 0) {
       *aUInt = integer;
diff --git a/accessible/src/generic/Accessible.cpp b/accessible/src/generic/Accessible.cpp
index b0620b337e04..b38b4789a452 100644
--- a/accessible/src/generic/Accessible.cpp
+++ b/accessible/src/generic/Accessible.cpp
@@ -3056,7 +3056,7 @@ Accessible::GetAttrValue(nsIAtom *aProperty, double *aValue)
   if (attrValue.IsEmpty())
     return NS_OK;
 
-  PRInt32 error = NS_OK;
+  nsresult error = NS_OK;
   double value = attrValue.ToDouble(&error);
   if (NS_SUCCEEDED(error))
     *aValue = value;
diff --git a/accessible/src/generic/FormControlAccessible.cpp b/accessible/src/generic/FormControlAccessible.cpp
index 43a22e22b916..a748cec161b7 100644
--- a/accessible/src/generic/FormControlAccessible.cpp
+++ b/accessible/src/generic/FormControlAccessible.cpp
@@ -111,7 +111,7 @@ ProgressMeterAccessible<Max>::GetMaximumValue(double* aMaximumValue)
 
   nsAutoString value;
   if (mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::max, value)) {
-    PRInt32 result = NS_OK;
+    nsresult result = NS_OK;
     *aMaximumValue = value.ToDouble(&result);
     return result;
   }
@@ -159,7 +159,7 @@ ProgressMeterAccessible<Max>::GetCurrentValue(double* aCurrentValue)
   if (attrValue.IsEmpty())
     return NS_OK;
 
-  PRInt32 error = NS_OK;
+  nsresult error = NS_OK;
   double value = attrValue.ToDouble(&error);
   if (NS_FAILED(error))
     return NS_OK; // Zero value because of wrong markup.
diff --git a/accessible/src/xforms/nsXFormsFormControlsAccessible.cpp b/accessible/src/xforms/nsXFormsFormControlsAccessible.cpp
index dc639888b4b8..914f2e957762 100644
--- a/accessible/src/xforms/nsXFormsFormControlsAccessible.cpp
+++ b/accessible/src/xforms/nsXFormsFormControlsAccessible.cpp
@@ -313,7 +313,7 @@ nsXFormsRangeAccessible::GetMaximumValue(double *aMaximumValue)
   nsresult rv = sXFormsService->GetRangeEnd(DOMNode, value);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  PRInt32 error = NS_OK;
+  nsresult error = NS_OK;
   *aMaximumValue = value.ToDouble(&error);
   return error;
 }
@@ -328,7 +328,7 @@ nsXFormsRangeAccessible::GetMinimumValue(double *aMinimumValue)
   nsresult rv = sXFormsService->GetRangeStart(DOMNode, value);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  PRInt32 error = NS_OK;
+  nsresult error = NS_OK;
   *aMinimumValue = value.ToDouble(&error);
   return error;
 }
@@ -343,7 +343,7 @@ nsXFormsRangeAccessible::GetMinimumIncrement(double *aMinimumIncrement)
   nsresult rv = sXFormsService->GetRangeStep(DOMNode, value);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  PRInt32 error = NS_OK;
+  nsresult error = NS_OK;
   *aMinimumIncrement = value.ToDouble(&error);
   return error;
 }
@@ -358,7 +358,7 @@ nsXFormsRangeAccessible::GetCurrentValue(double *aCurrentValue)
   nsresult rv = sXFormsService->GetValue(DOMNode, value);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  PRInt32 error = NS_OK;
+  nsresult error = NS_OK;
   *aCurrentValue = value.ToDouble(&error);
   return error;
 }
diff --git a/accessible/src/xul/XULMenuAccessible.cpp b/accessible/src/xul/XULMenuAccessible.cpp
index 5adc532d572a..13685ce50ee5 100644
--- a/accessible/src/xul/XULMenuAccessible.cpp
+++ b/accessible/src/xul/XULMenuAccessible.cpp
@@ -213,7 +213,7 @@ XULMenuitemAccessible::KeyboardShortcut() const
   if (keyStr.IsEmpty()) {
     nsAutoString keyCodeStr;
     keyElm->GetAttr(kNameSpaceID_None, nsGkAtoms::keycode, keyCodeStr);
-    PRUint32 errorCode;
+    nsresult errorCode;
     key = keyStr.ToInteger(&errorCode, kAutoDetect);
   } else {
     key = keyStr[0];
diff --git a/accessible/src/xul/XULSliderAccessible.cpp b/accessible/src/xul/XULSliderAccessible.cpp
index 8398f3ab7317..defbf002b326 100644
--- a/accessible/src/xul/XULSliderAccessible.cpp
+++ b/accessible/src/xul/XULSliderAccessible.cpp
@@ -223,7 +223,7 @@ XULSliderAccessible::GetSliderAttr(nsIAtom* aName, double* aValue)
   if (attrValue.IsEmpty())
     return NS_OK;
 
-  PRInt32 error = NS_OK;
+  nsresult error = NS_OK;
   double value = attrValue.ToDouble(&error);
   if (NS_SUCCEEDED(error))
     *aValue = value;
diff --git a/content/base/src/Link.cpp b/content/base/src/Link.cpp
index e9d8b4591510..a10a30eda457 100644
--- a/content/base/src/Link.cpp
+++ b/content/base/src/Link.cpp
@@ -188,7 +188,7 @@ Link::SetHost(const nsAString &aHost)
     if (iter != end) {
       nsAutoString portStr(Substring(iter, end));
       nsresult rv;
-      PRInt32 port = portStr.ToInteger((PRInt32 *)&rv);
+      PRInt32 port = portStr.ToInteger(&rv);
       if (NS_SUCCEEDED(rv)) {
         (void)uri->SetPort(port);
       }
@@ -254,7 +254,7 @@ Link::SetPort(const nsAString &aPort)
 
   nsresult rv;
   nsAutoString portStr(aPort);
-  PRInt32 port = portStr.ToInteger((PRInt32 *)&rv);
+  PRInt32 port = portStr.ToInteger(&rv);
   if (NS_FAILED(rv)) {
     return NS_OK;
   }
diff --git a/content/base/src/nsAttrValue.cpp b/content/base/src/nsAttrValue.cpp
index aace0bc7e772..f2a329a1e57f 100644
--- a/content/base/src/nsAttrValue.cpp
+++ b/content/base/src/nsAttrValue.cpp
@@ -1462,7 +1462,7 @@ bool nsAttrValue::ParseDoubleValue(const nsAString& aString)
 {
   ResetIfSet();
 
-  PRInt32 ec;
+  nsresult ec;
   double val = PromiseFlatString(aString).ToDouble(&ec);
   if (NS_FAILED(ec)) {
     return false;
diff --git a/content/base/src/nsContentUtils.cpp b/content/base/src/nsContentUtils.cpp
index 48aceac9d9b2..4e48af843aa8 100644
--- a/content/base/src/nsContentUtils.cpp
+++ b/content/base/src/nsContentUtils.cpp
@@ -1261,8 +1261,8 @@ nsContentUtils::ParseIntMarginValue(const nsAString& aString, nsIntMargin& resul
     if (end <= 0)
       return false;
 
-    PRInt32 ec, val = 
-      nsString(Substring(marginStr, start, end)).ToInteger(&ec);
+    nsresult ec;
+    PRInt32 val = nsString(Substring(marginStr, start, end)).ToInteger(&ec);
     if (NS_FAILED(ec))
       return false;
 
@@ -5020,11 +5020,10 @@ nsContentUtils::GetViewportInfo(nsIDocument *aDocument)
     return ret;
   }
 
-  PRInt32 errorCode;
-
   nsAutoString minScaleStr;
   aDocument->GetHeaderData(nsGkAtoms::minimum_scale, minScaleStr);
 
+  nsresult errorCode;
   float scaleMinFloat = minScaleStr.ToFloat(&errorCode);
 
   if (errorCode) {
@@ -5039,7 +5038,7 @@ nsContentUtils::GetViewportInfo(nsIDocument *aDocument)
 
   // We define a special error code variable for the scale and max scale,
   // because they are used later (see the width calculations).
-  PRInt32 scaleMaxErrorCode;
+  nsresult scaleMaxErrorCode;
   float scaleMaxFloat = maxScaleStr.ToFloat(&scaleMaxErrorCode);
 
   if (scaleMaxErrorCode) {
@@ -5052,7 +5051,7 @@ nsContentUtils::GetViewportInfo(nsIDocument *aDocument)
   nsAutoString scaleStr;
   aDocument->GetHeaderData(nsGkAtoms::viewport_initial_scale, scaleStr);
 
-  PRInt32 scaleErrorCode;
+  nsresult scaleErrorCode;
   float scaleFloat = scaleStr.ToFloat(&scaleErrorCode);
   scaleFloat = NS_MIN(scaleFloat, scaleMaxFloat);
   scaleFloat = NS_MAX(scaleFloat, scaleMinFloat);
diff --git a/content/base/src/nsHTMLContentSerializer.cpp b/content/base/src/nsHTMLContentSerializer.cpp
index 6d86d5361e41..07f44b2c53fd 100644
--- a/content/base/src/nsHTMLContentSerializer.cpp
+++ b/content/base/src/nsHTMLContentSerializer.cpp
@@ -241,7 +241,7 @@ nsHTMLContentSerializer::AppendElementStart(Element* aElement,
 
     aElement->GetAttr(kNameSpaceID_None, nsGkAtoms::start, start);
     if (!start.IsEmpty()){
-      PRInt32 rv = 0;
+      nsresult rv = NS_OK;
       startAttrVal = start.ToInteger(&rv);
       //If OL has "start" attribute, first LI element has to start with that value
       //Therefore subtracting 1 as all the LI elements are incrementing it before using it;
diff --git a/content/base/src/nsPlainTextSerializer.cpp b/content/base/src/nsPlainTextSerializer.cpp
index 1df76ec14d29..2a84450463c4 100644
--- a/content/base/src/nsPlainTextSerializer.cpp
+++ b/content/base/src/nsPlainTextSerializer.cpp
@@ -480,7 +480,7 @@ nsPlainTextSerializer::DoOpenContainer(nsIAtom* aTag)
                             : style.Length() - widthOffset);
           nsAutoString widthstr;
           style.Mid(widthstr, widthOffset+6, length);
-          PRInt32 err;
+          nsresult err;
           PRInt32 col = widthstr.ToInteger(&err);
 
           if (NS_SUCCEEDED(err)) {
@@ -563,7 +563,7 @@ nsPlainTextSerializer::DoOpenContainer(nsIAtom* aTag)
         nsAutoString startAttr;
         PRInt32 startVal = 1;
         if (NS_SUCCEEDED(GetAttributeValue(nsGkAtoms::start, startAttr))) {
-          PRInt32 rv = 0;
+          nsresult rv = NS_OK;
           startVal = startAttr.ToInteger(&rv);
           if (NS_FAILED(rv))
             startVal = 1;
@@ -581,7 +581,7 @@ nsPlainTextSerializer::DoOpenContainer(nsIAtom* aTag)
       if (mOLStackIndex > 0) {
         nsAutoString valueAttr;
         if (NS_SUCCEEDED(GetAttributeValue(nsGkAtoms::value, valueAttr))) {
-          PRInt32 rv = 0;
+          nsresult rv = NS_OK;
           PRInt32 valueAttrVal = valueAttr.ToInteger(&rv);
           if (NS_SUCCEEDED(rv))
             mOLStack[mOLStackIndex-1] = valueAttrVal;
diff --git a/content/base/src/nsXHTMLContentSerializer.cpp b/content/base/src/nsXHTMLContentSerializer.cpp
index 2876461da2ed..4a3df2a1bb2d 100644
--- a/content/base/src/nsXHTMLContentSerializer.cpp
+++ b/content/base/src/nsXHTMLContentSerializer.cpp
@@ -254,7 +254,7 @@ nsXHTMLContentSerializer::SerializeAttributes(nsIContent* aContent,
       PRInt32 startAttrVal = 0;
       aContent->GetAttr(kNameSpaceID_None, nsGkAtoms::start, start);
       if (!start.IsEmpty()) {
-        PRInt32 rv = 0;
+        nsresult rv = NS_OK;
         startAttrVal = start.ToInteger(&rv);
         //If OL has "start" attribute, first LI element has to start with that value
         //Therefore subtracting 1 as all the LI elements are incrementing it before using it;
@@ -920,7 +920,7 @@ nsXHTMLContentSerializer::SerializeLIValueAttribute(nsIContent* aElement,
           offset++;
         else {
           found = true;
-          PRInt32 rv = 0;
+          nsresult rv = NS_OK;
           startVal = valueStr.ToInteger(&rv);
         }
       }
diff --git a/content/html/content/src/nsHTMLFormElement.cpp b/content/html/content/src/nsHTMLFormElement.cpp
index 76249a100ed6..3e429e928b9c 100644
--- a/content/html/content/src/nsHTMLFormElement.cpp
+++ b/content/html/content/src/nsHTMLFormElement.cpp
@@ -1794,7 +1794,7 @@ NS_IMETHODIMP
 nsHTMLFormElement::OnStateChange(nsIWebProgress* aWebProgress,
                                  nsIRequest* aRequest,
                                  PRUint32 aStateFlags,
-                                 PRUint32 aStatus)
+                                 nsresult aStatus)
 {
   // If STATE_STOP is never fired for any reason (redirect?  Failed state
   // change?) the form element will leak.  It will be kept around by the
diff --git a/content/html/content/src/nsHTMLFrameSetElement.cpp b/content/html/content/src/nsHTMLFrameSetElement.cpp
index 52a2dc73c4aa..203edde4e142 100644
--- a/content/html/content/src/nsHTMLFrameSetElement.cpp
+++ b/content/html/content/src/nsHTMLFrameSetElement.cpp
@@ -275,7 +275,7 @@ nsHTMLFrameSetElement::ParseRowCol(const nsAString & aValue,
       }
       else {
         // Otherwise just convert to integer.
-        PRInt32 err;
+        nsresult err;
         specs[i].mValue = token.ToInteger(&err);
         if (err) {
           specs[i].mValue = 0;
diff --git a/content/html/content/src/nsHTMLInputElement.cpp b/content/html/content/src/nsHTMLInputElement.cpp
index 04780777712c..5e26f096acc6 100644
--- a/content/html/content/src/nsHTMLInputElement.cpp
+++ b/content/html/content/src/nsHTMLInputElement.cpp
@@ -1005,7 +1005,7 @@ nsHTMLInputElement::GetValueAsDouble() const
 {
   double doubleValue;
   nsAutoString stringValue;
-  PRInt32 ec;
+  nsresult ec;
 
   GetValueInternal(stringValue);
   doubleValue = stringValue.ToDouble(&ec);
@@ -1107,7 +1107,7 @@ nsHTMLInputElement::GetMinAsDouble() const
   nsAutoString minStr;
   GetAttr(kNameSpaceID_None, nsGkAtoms::min, minStr);
 
-  PRInt32 ec;
+  nsresult ec;
   double min = minStr.ToDouble(&ec);
   return NS_SUCCEEDED(ec) ? min : MOZ_DOUBLE_NaN();
 }
@@ -1125,7 +1125,7 @@ nsHTMLInputElement::GetMaxAsDouble() const
   nsAutoString maxStr;
   GetAttr(kNameSpaceID_None, nsGkAtoms::max, maxStr);
 
-  PRInt32 ec;
+  nsresult ec;
   double max = maxStr.ToDouble(&ec);
   return NS_SUCCEEDED(ec) ? max : MOZ_DOUBLE_NaN();
 }
@@ -2661,7 +2661,7 @@ nsHTMLInputElement::SanitizeValue(nsAString& aValue)
       break;
     case NS_FORM_INPUT_NUMBER:
       {
-        PRInt32 ec;
+        nsresult ec;
         PromiseFlatString(aValue).ToDouble(&ec);
         if (NS_FAILED(ec)) {
           aValue.Truncate();
@@ -3863,7 +3863,7 @@ nsHTMLInputElement::GetStep() const
       return kStepAny;
     }
 
-    PRInt32 ec;
+    nsresult ec;
     // NOTE: should be multiplied by defaultStepScaleFactor,
     // which is 1 for type=number.
     step = stepStr.ToDouble(&ec);
diff --git a/content/html/content/src/nsMediaFragmentURIParser.cpp b/content/html/content/src/nsMediaFragmentURIParser.cpp
index 7a8a762594a4..8b8c11565e3f 100644
--- a/content/html/content/src/nsMediaFragmentURIParser.cpp
+++ b/content/html/content/src/nsMediaFragmentURIParser.cpp
@@ -106,7 +106,7 @@ bool nsMediaFragmentURIParser::ParseNPTSec(nsDependentSubstring& aString, double
   }
 
   nsDependentSubstring n(aString, 0, index);
-  PRInt32 ec;
+  nsresult ec;
   PRInt32 s = PromiseFlatString(n).ToInteger(&ec);
   if (NS_FAILED(ec)) {
     return false;
@@ -162,7 +162,7 @@ bool nsMediaFragmentURIParser::ParseNPTFraction(nsDependentSubstring& aString, d
 
     if (index > 1) {
       nsDependentSubstring number(aString, 0, index);
-      PRInt32 ec;
+      nsresult ec;
       fraction = PromiseFlatString(number).ToDouble(&ec);
       if (NS_FAILED(ec)) {
         return false;
@@ -211,7 +211,7 @@ bool nsMediaFragmentURIParser::ParseNPTHH(nsDependentSubstring& aString, PRUint3
   }
 
   nsDependentSubstring n(aString, 0, index);
-  PRInt32 ec;
+  nsresult ec;
   PRInt32 u = PromiseFlatString(n).ToInteger(&ec);
   if (NS_FAILED(ec)) {
     return false;
@@ -235,8 +235,7 @@ bool nsMediaFragmentURIParser::ParseNPTSS(nsDependentSubstring& aString, PRUint3
 
   if (IsDigit(aString[0]) && IsDigit(aString[1])) {
     nsDependentSubstring n(aString, 0, 2);
-    PRInt32 ec;
-
+    nsresult ec;
     PRInt32 u = PromiseFlatString(n).ToInteger(&ec);
     if (NS_FAILED(ec)) {
       return false;
diff --git a/content/mathml/content/src/nsMathMLElement.cpp b/content/mathml/content/src/nsMathMLElement.cpp
index 1cbdc627ac44..73870e5fa153 100644
--- a/content/mathml/content/src/nsMathMLElement.cpp
+++ b/content/mathml/content/src/nsMathMLElement.cpp
@@ -334,7 +334,7 @@ nsMathMLElement::ParseNumericValue(const nsString& aString,
   }
 
   // Convert number to floating point
-  PRInt32 errorCode;
+  nsresult errorCode;
   float floatValue = number.ToFloat(&errorCode);
   if (NS_FAILED(errorCode))
     return false;
@@ -397,7 +397,7 @@ nsMathMLElement::MapMathMLAttributesInto(const nsMappedAttributes* aAttributes,
       str.CompressWhitespace();
       // MathML numbers can't have leading '+'
       if (str.Length() > 0 && str.CharAt(0) != '+') {
-        PRInt32 errorCode;
+        nsresult errorCode;
         float floatValue = str.ToFloat(&errorCode);
         // Negative scriptsizemultipliers are not parsed
         if (NS_SUCCEEDED(errorCode) && floatValue >= 0.0f) {
@@ -443,7 +443,7 @@ nsMathMLElement::MapMathMLAttributesInto(const nsMappedAttributes* aAttributes,
       nsAutoString str(value->GetStringValue());
       str.CompressWhitespace();
       if (str.Length() > 0) {
-        PRInt32 errorCode;
+        nsresult errorCode;
         PRInt32 intValue = str.ToInteger(&errorCode);
         if (NS_SUCCEEDED(errorCode)) {
           // This is kind of cheesy ... if the scriptlevel has a sign,
diff --git a/content/media/MediaResource.cpp b/content/media/MediaResource.cpp
index 83a34d6b4fba..db01f70d8b6e 100644
--- a/content/media/MediaResource.cpp
+++ b/content/media/MediaResource.cpp
@@ -180,7 +180,7 @@ ChannelMediaResource::OnStartRequest(nsIRequest* aRequest)
       // 4) X-Content-Duration.
       // 5) Perform a seek in the decoder to find the value.
       nsCAutoString durationText;
-      PRInt32 ec = 0;
+      nsresult ec = NS_OK;
       rv = hc->GetResponseHeader(NS_LITERAL_CSTRING("Content-Duration"), durationText);
       if (NS_FAILED(rv)) {
         rv = hc->GetResponseHeader(NS_LITERAL_CSTRING("X-AMZ-Meta-Content-Duration"), durationText);
diff --git a/content/xul/content/src/nsXULContextMenuBuilder.cpp b/content/xul/content/src/nsXULContextMenuBuilder.cpp
index f74d3c4f9b82..76682af6d0d5 100644
--- a/content/xul/content/src/nsXULContextMenuBuilder.cpp
+++ b/content/xul/content/src/nsXULContextMenuBuilder.cpp
@@ -196,7 +196,7 @@ nsXULContextMenuBuilder::Init(nsIDOMDocumentFragment* aDocumentFragment,
 NS_IMETHODIMP
 nsXULContextMenuBuilder::Click(const nsAString& aGeneratedItemId)
 {
-  PRInt32 rv;
+  nsresult rv;
   PRInt32 idx = nsString(aGeneratedItemId).ToInteger(&rv);
   if (NS_SUCCEEDED(rv)) {
     nsCOMPtr<nsIDOMHTMLElement> element = mElements.SafeObjectAt(idx);
diff --git a/content/xul/document/src/nsXULDocument.cpp b/content/xul/document/src/nsXULDocument.cpp
index 2018cd39cca3..88f2dd86a55b 100644
--- a/content/xul/document/src/nsXULDocument.cpp
+++ b/content/xul/document/src/nsXULDocument.cpp
@@ -4422,7 +4422,7 @@ nsXULDocument::InsertElement(nsIContent* aParent, nsIContent* aChild,
         if (!posStr.IsEmpty()) {
             nsresult rv;
             // Positions are one-indexed.
-            PRInt32 pos = posStr.ToInteger(reinterpret_cast<PRInt32*>(&rv));
+            PRInt32 pos = posStr.ToInteger(&rv);
             // Note: if the insertion index (which is |pos - 1|) would be less
             // than 0 or greater than the number of children aParent has, then
             // don't insert, since the position is bogus.  Just skip on to
diff --git a/content/xul/templates/src/nsTemplateRule.cpp b/content/xul/templates/src/nsTemplateRule.cpp
index 518260863e8d..0ebf2d2eef8b 100644
--- a/content/xul/templates/src/nsTemplateRule.cpp
+++ b/content/xul/templates/src/nsTemplateRule.cpp
@@ -155,7 +155,7 @@ nsTemplateCondition::CheckMatchStrings(const nsAString& aLeftString,
             case eGreater:
             {
                 // non-numbers always compare false
-                PRInt32 err;
+                nsresult err;
                 PRInt32 leftint = PromiseFlatString(aLeftString).ToInteger(&err);
                 if (NS_SUCCEEDED(err)) {
                     PRInt32 rightint = PromiseFlatString(aRightString).ToInteger(&err);
diff --git a/content/xul/templates/src/nsXULContentBuilder.cpp b/content/xul/templates/src/nsXULContentBuilder.cpp
index d05c3062455f..fed69cf4a0e4 100644
--- a/content/xul/templates/src/nsXULContentBuilder.cpp
+++ b/content/xul/templates/src/nsXULContentBuilder.cpp
@@ -1889,7 +1889,7 @@ nsXULContentBuilder::InsertSortedNode(nsIContent* aContainer,
         if (!staticValue.IsEmpty())
         {
             // found "static" XUL element count hint
-            PRInt32 strErr = 0;
+            nsresult strErr = NS_OK;
             staticCount = staticValue.ToInteger(&strErr);
             if (strErr)
                 staticCount = 0;
diff --git a/content/xul/templates/src/nsXULSortService.cpp b/content/xul/templates/src/nsXULSortService.cpp
index 8fc5e77b04e8..3f5316fa1ee1 100644
--- a/content/xul/templates/src/nsXULSortService.cpp
+++ b/content/xul/templates/src/nsXULSortService.cpp
@@ -453,7 +453,7 @@ XULSortServiceImpl::CompareValues(const nsAString& aLeft,
                                   PRUint32 aSortHints)
 {
   if (aSortHints & SORT_INTEGER) {
-    PRInt32 err;
+    nsresult err;
     PRInt32 leftint = PromiseFlatString(aLeft).ToInteger(&err);
     if (NS_SUCCEEDED(err)) {
       PRInt32 rightint = PromiseFlatString(aRight).ToInteger(&err);
diff --git a/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp b/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp
index 1be5cd1a9771..dbef239c52e4 100644
--- a/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp
+++ b/content/xul/templates/src/nsXULTemplateQueryProcessorRDF.cpp
@@ -1321,7 +1321,7 @@ nsXULTemplateQueryProcessorRDF::ParseLiteral(const nsString& aParseType,
 
     if (aParseType.EqualsLiteral(PARSE_TYPE_INTEGER)) {
         nsCOMPtr<nsIRDFInt> intLiteral;
-        PRInt32 errorCode;
+        nsresult errorCode;
         PRInt32 intValue = aValue.ToInteger(&errorCode);
         if (NS_FAILED(errorCode))
             return NS_ERROR_FAILURE;
diff --git a/docshell/base/nsIContentViewer.idl b/docshell/base/nsIContentViewer.idl
index 977f20f12d69..cafe7e854082 100644
--- a/docshell/base/nsIContentViewer.idl
+++ b/docshell/base/nsIContentViewer.idl
@@ -37,7 +37,7 @@ interface nsIContentViewer : nsISupports
   attribute nsISupports container;
 
   void loadStart(in nsISupports aDoc);
-  void loadComplete(in unsigned long aStatus);
+  void loadComplete(in nsresult aStatus);
 
   /**
    * Checks if the document wants to prevent unloading by firing beforeunload on
diff --git a/dom/base/nsDOMClassInfo.cpp b/dom/base/nsDOMClassInfo.cpp
index 6efd4604883d..63c01c3f13c6 100644
--- a/dom/base/nsDOMClassInfo.cpp
+++ b/dom/base/nsDOMClassInfo.cpp
@@ -10292,7 +10292,7 @@ nsStorage2SH::NewResolve(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
 
   JSString *jsstr = IdToString(cx, id);
   if (!jsstr) {
-    return JS_FALSE;
+    return NS_OK;
   }
 
   JSObject *proto = ::JS_GetPrototype(realObj);
diff --git a/dom/base/nsDOMException.cpp b/dom/base/nsDOMException.cpp
index 0ee5ee718453..3bcd71110579 100644
--- a/dom/base/nsDOMException.cpp
+++ b/dom/base/nsDOMException.cpp
@@ -70,7 +70,7 @@ static struct ResultStruct
   const char* mMessage;
 } gDOMErrorMsgMap[] = {
 #include "domerr.msg"
-  {0, 0, nullptr, nullptr}   // sentinel to mark end of array
+  {NS_OK, 0, nullptr, nullptr}   // sentinel to mark end of array
 };
 
 #undef DOM4_MSG_DEF
@@ -205,7 +205,7 @@ nsDOMException::GetMessageMoz(char **aMessage)
 }
 
 NS_IMETHODIMP
-nsDOMException::GetResult(PRUint32* aResult)
+nsDOMException::GetResult(nsresult* aResult)
 {
   NS_ENSURE_ARG_POINTER(aResult);
 
diff --git a/dom/base/nsFocusManager.cpp b/dom/base/nsFocusManager.cpp
index b678bafeae9a..0108e0dcebbe 100644
--- a/dom/base/nsFocusManager.cpp
+++ b/dom/base/nsFocusManager.cpp
@@ -2926,7 +2926,8 @@ nsFocusManager::GetNextTabIndex(nsIContent* aParent,
 
       nsAutoString tabIndexStr;
       child->GetAttr(kNameSpaceID_None, nsGkAtoms::tabindex, tabIndexStr);
-      PRInt32 ec, val = tabIndexStr.ToInteger(&ec);
+      nsresult ec;
+      PRInt32 val = tabIndexStr.ToInteger(&ec);
       if (NS_SUCCEEDED (ec) && val > aCurrentTabIndex && val != tabIndex) {
         tabIndex = (tabIndex == 0 || val < tabIndex) ? val : tabIndex;
       }
@@ -2945,7 +2946,8 @@ nsFocusManager::GetNextTabIndex(nsIContent* aParent,
 
       nsAutoString tabIndexStr;
       child->GetAttr(kNameSpaceID_None, nsGkAtoms::tabindex, tabIndexStr);
-      PRInt32 ec, val = tabIndexStr.ToInteger(&ec);
+      nsresult ec;
+      PRInt32 val = tabIndexStr.ToInteger(&ec);
       if (NS_SUCCEEDED (ec)) {
         if ((aCurrentTabIndex == 0 && val > tabIndex) ||
             (val < aCurrentTabIndex && val > tabIndex) ) {
diff --git a/dom/devicestorage/nsDeviceStorage.cpp b/dom/devicestorage/nsDeviceStorage.cpp
index d59d32c57362..39817112c3aa 100644
--- a/dom/devicestorage/nsDeviceStorage.cpp
+++ b/dom/devicestorage/nsDeviceStorage.cpp
@@ -961,7 +961,7 @@ public:
       // the one and only TabChild.
       TabChild* child = GetTabChildFrom(mWindow->GetDocShell());
       if (!child)
-	return false;
+        return NS_OK;
 
       // Retain a reference so the object isn't deleted without IPDL's knowledge.
       // Corresponding release occurs in DeallocPContentPermissionRequest.
@@ -1457,7 +1457,7 @@ nsDOMDeviceStorage::EnumerateInternal(const JS::Value & aName,
     // the one and only TabChild.
     TabChild* child = GetTabChildFrom(win->GetDocShell());
     if (!child)
-      return false;
+      return NS_OK;
 
     // Retain a reference so the object isn't deleted without IPDL's knowledge.
     // Corresponding release occurs in DeallocPContentPermissionRequest.
diff --git a/dom/indexedDB/IDBTransaction.cpp b/dom/indexedDB/IDBTransaction.cpp
index 235e28aa441d..79e196313c24 100644
--- a/dom/indexedDB/IDBTransaction.cpp
+++ b/dom/indexedDB/IDBTransaction.cpp
@@ -305,12 +305,12 @@ IDBTransaction::ReleaseSavepoint()
   nsCOMPtr<mozIStorageStatement> stmt = GetCachedStatement(NS_LITERAL_CSTRING(
     "RELEASE SAVEPOINT " SAVEPOINT_NAME
   ));
-  NS_ENSURE_TRUE(stmt, false);
+  NS_ENSURE_TRUE(stmt, NS_OK);
 
   mozStorageStatementScoper scoper(stmt);
 
   nsresult rv = stmt->Execute();
-  NS_ENSURE_SUCCESS(rv, false);
+  NS_ENSURE_SUCCESS(rv, NS_OK);
 
   --mSavepointCount;
 
diff --git a/dom/system/gonk/Volume.cpp b/dom/system/gonk/Volume.cpp
index ffa596a07870..20dda8aae68f 100644
--- a/dom/system/gonk/Volume.cpp
+++ b/dom/system/gonk/Volume.cpp
@@ -155,7 +155,7 @@ Volume::HandleVoldResponse(int aResponseCode, nsCWhitespaceTokenizer &aTokenizer
       //
       nsDependentCSubstring mntPoint(aTokenizer.nextToken());
       SetMountPoint(mntPoint);
-      PRInt32 errCode;
+      nsresult errCode;
       nsCString state(aTokenizer.nextToken());
       SetState((STATE)state.ToInteger(&errCode));
       break;
@@ -170,7 +170,7 @@ Volume::HandleVoldResponse(int aResponseCode, nsCWhitespaceTokenizer &aTokenizer
       while (aTokenizer.hasMoreTokens()) {
         nsCAutoString token(aTokenizer.nextToken());
         if (token.Equals("to")) {
-          PRInt32 errCode;
+          nsresult errCode;
           token = aTokenizer.nextToken();
           SetState((STATE)token.ToInteger(&errCode));
           break;
diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index d398f26a599a..874a13d482f8 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -1794,7 +1794,7 @@ WorkerRunnable::Run()
 
   JSAutoEnterCompartment ac;
   if (targetCompartmentObject && !ac.enter(cx, targetCompartmentObject)) {
-    return false;
+    return NS_OK;
   }
 
   bool result = WorkerRun(cx, mWorkerPrivate);
diff --git a/editor/libeditor/base/nsEditor.cpp b/editor/libeditor/base/nsEditor.cpp
index d15176467827..c4f49cf2de05 100644
--- a/editor/libeditor/base/nsEditor.cpp
+++ b/editor/libeditor/base/nsEditor.cpp
@@ -3285,7 +3285,7 @@ nsEditor::GetNextNode(nsINode* aParentNode,
   // and want the next one.
   if (aNoBlockCrossing && IsBlockNode(aParentNode)) {
     // don't cross out of parent block
-    return NS_OK;
+    return nullptr;
   }
 
   return GetNextNode(aParentNode, aEditableNode, aNoBlockCrossing);
diff --git a/editor/libeditor/html/nsHTMLAbsPosition.cpp b/editor/libeditor/html/nsHTMLAbsPosition.cpp
index 7b59a024d1ae..9d4143186818 100644
--- a/editor/libeditor/html/nsHTMLAbsPosition.cpp
+++ b/editor/libeditor/html/nsHTMLAbsPosition.cpp
@@ -233,7 +233,7 @@ nsHTMLEditor::GetElementZIndex(nsIDOMElement * aElement,
   }
 
   if (!zIndexStr.EqualsLiteral("auto")) {
-    PRInt32 errorCode;
+    nsresult errorCode;
     *aZindex = zIndexStr.ToInteger(&errorCode);
   }
 
diff --git a/editor/libeditor/html/nsHTMLCSSUtils.cpp b/editor/libeditor/html/nsHTMLCSSUtils.cpp
index b8249c0a440b..c4a6567dfb35 100644
--- a/editor/libeditor/html/nsHTMLCSSUtils.cpp
+++ b/editor/libeditor/html/nsHTMLCSSUtils.cpp
@@ -1155,7 +1155,7 @@ nsHTMLCSSUtils::IsCSSEquivalentToHTMLInlineStyleSet(nsIDOMNode *aNode,
         valueString.AssignLiteral("bold");
       } else {
         PRInt32 weight = 0;
-        PRInt32 errorCode;
+        nsresult errorCode;
         nsAutoString value(valueString);
         weight = value.ToInteger(&errorCode, 10);
         if (400 < weight) {
diff --git a/editor/libeditor/html/nsHTMLDataTransfer.cpp b/editor/libeditor/html/nsHTMLDataTransfer.cpp
index 7853ffc882f2..6d2cb9e94106 100644
--- a/editor/libeditor/html/nsHTMLDataTransfer.cpp
+++ b/editor/libeditor/html/nsHTMLDataTransfer.cpp
@@ -1043,7 +1043,7 @@ FindIntegerAfterString(const char *aLeadingString,
     return false;
 
   nsCAutoString numStr(Substring(aCStr, numFront, numBack-numFront));
-  PRInt32 errorCode;
+  nsresult errorCode;
   foundNumber = numStr.ToInteger(&errorCode);
   return true;
 }
@@ -2289,12 +2289,13 @@ nsresult nsHTMLEditor::CreateDOMFragmentFromPaste(const nsAString &aInputString,
   nsAutoString numstr1, numstr2;
   if (!aInfoStr.IsEmpty())
   {
-    PRInt32 err, sep, num;
+    PRInt32 sep, num;
     sep = aInfoStr.FindChar((PRUnichar)',');
     numstr1 = Substring(aInfoStr, 0, sep);
     numstr2 = Substring(aInfoStr, sep+1, aInfoStr.Length() - (sep+1));
 
     // Move the start and end children.
+    nsresult err;
     num = numstr1.ToInteger(&err);
     while (num--)
     {
diff --git a/editor/txtsvc/src/nsTextServicesDocument.cpp b/editor/txtsvc/src/nsTextServicesDocument.cpp
index be96ac7367f4..8d2bf572a7a2 100644
--- a/editor/txtsvc/src/nsTextServicesDocument.cpp
+++ b/editor/txtsvc/src/nsTextServicesDocument.cpp
@@ -1867,13 +1867,13 @@ nsTextServicesDocument::DidJoinNodes(nsIDOMNode  *aLeftNode,
   // Make sure that both nodes are text nodes -- otherwise we don't care.
 
   result = aLeftNode->GetNodeType(&type);
-  NS_ENSURE_SUCCESS(result, false);
+  NS_ENSURE_SUCCESS(result, NS_OK);
   if (nsIDOMNode::TEXT_NODE != type) {
     return NS_OK;
   }
 
   result = aRightNode->GetNodeType(&type);
-  NS_ENSURE_SUCCESS(result, false);
+  NS_ENSURE_SUCCESS(result, NS_OK);
   if (nsIDOMNode::TEXT_NODE != type) {
     return NS_OK;
   }
diff --git a/embedding/components/printingui/src/unixshared/nsPrintProgress.cpp b/embedding/components/printingui/src/unixshared/nsPrintProgress.cpp
index 8c4f9c6fc7c1..e5b1d9f5f611 100644
--- a/embedding/components/printingui/src/unixshared/nsPrintProgress.cpp
+++ b/embedding/components/printingui/src/unixshared/nsPrintProgress.cpp
@@ -27,7 +27,7 @@ nsPrintProgress::nsPrintProgress(nsIPrintSettings* aPrintSettings)
   m_closeProgress = false;
   m_processCanceled = false;
   m_pendingStateFlags = -1;
-  m_pendingStateValue = 0;
+  m_pendingStateValue = NS_OK;
   m_PrintSetting = aPrintSettings;
 }
 
@@ -115,7 +115,7 @@ NS_IMETHODIMP nsPrintProgress::SetProcessCanceledByUser(bool aProcessCanceledByU
   if(m_PrintSetting)
     m_PrintSetting->SetIsCancelled(true);
   m_processCanceled = aProcessCanceledByUser;
-  OnStateChange(nullptr, nullptr, nsIWebProgressListener::STATE_STOP, false);
+  OnStateChange(nullptr, nullptr, nsIWebProgressListener::STATE_STOP, NS_OK);
   return NS_OK;
 }
 
@@ -134,7 +134,7 @@ NS_IMETHODIMP nsPrintProgress::RegisterListener(nsIWebProgressListener * listene
   {
     m_listenerList->AppendElement(listener);
     if (m_closeProgress || m_processCanceled)
-      listener->OnStateChange(nullptr, nullptr, nsIWebProgressListener::STATE_STOP, 0);
+      listener->OnStateChange(nullptr, nullptr, nsIWebProgressListener::STATE_STOP, NS_OK);
     else
     {
       listener->OnStatusChange(nullptr, nullptr, 0, m_pendingStatus.get());
diff --git a/embedding/components/printingui/src/unixshared/nsPrintProgress.h b/embedding/components/printingui/src/unixshared/nsPrintProgress.h
index 33c4bf4e232d..f1472f8c1f91 100644
--- a/embedding/components/printingui/src/unixshared/nsPrintProgress.h
+++ b/embedding/components/printingui/src/unixshared/nsPrintProgress.h
@@ -34,7 +34,7 @@ private:
   bool                              m_processCanceled;
   nsString                          m_pendingStatus;
   PRInt32                           m_pendingStateFlags;
-  PRInt32                           m_pendingStateValue;
+  nsresult                          m_pendingStateValue;
   nsCOMPtr<nsIDOMWindow>            m_dialog;
   nsCOMPtr<nsISupportsArray>        m_listenerList;
   nsCOMPtr<nsIObserver>             m_observer;
diff --git a/extensions/cookie/nsPermissionManager.cpp b/extensions/cookie/nsPermissionManager.cpp
index ef3b8a863336..1f8bb65cc38d 100644
--- a/extensions/cookie/nsPermissionManager.cpp
+++ b/extensions/cookie/nsPermissionManager.cpp
@@ -1173,7 +1173,7 @@ nsPermissionManager::Import()
     if (lineArray[0].EqualsLiteral(kMatchTypeHost) &&
         lineArray.Length() == 4) {
       
-      PRInt32 error;
+      nsresult error;
       PRUint32 permission = lineArray[2].ToInteger(&error);
       if (error)
         continue;
diff --git a/gfx/thebes/gfxUserFontSet.h b/gfx/thebes/gfxUserFontSet.h
index 40680dadd126..c29d0c5afec8 100644
--- a/gfx/thebes/gfxUserFontSet.h
+++ b/gfx/thebes/gfxUserFontSet.h
@@ -259,7 +259,7 @@ protected:
     virtual nsresult LogMessage(gfxProxyFontEntry *aProxy,
                                 const char *aMessage,
                                 PRUint32 aFlags = nsIScriptError::errorFlag,
-                                nsresult aStatus = 0) = 0;
+                                nsresult aStatus = NS_OK) = 0;
 
     const PRUint8* SanitizeOpenTypeData(gfxProxyFontEntry *aProxy,
                                         const PRUint8* aData,
diff --git a/intl/unicharutil/src/nsEntityConverter.cpp b/intl/unicharutil/src/nsEntityConverter.cpp
index beb749c1d5bc..a79734e2ad65 100644
--- a/intl/unicharutil/src/nsEntityConverter.cpp
+++ b/intl/unicharutil/src/nsEntityConverter.cpp
@@ -43,7 +43,7 @@ nsEntityConverter::LoadVersionPropertyFile()
     nsresult rv = bundleService->CreateBundle(url.get(), getter_AddRefs(entities));
     if (NS_FAILED(rv)) return rv;
     
-    PRInt32	result;
+    nsresult result;
 
     nsAutoString key;
     nsXPIDLString value;
diff --git a/js/xpconnect/src/XPCComponents.cpp b/js/xpconnect/src/XPCComponents.cpp
index f25625191762..b467fd4e84f4 100644
--- a/js/xpconnect/src/XPCComponents.cpp
+++ b/js/xpconnect/src/XPCComponents.cpp
@@ -42,7 +42,7 @@ using mozilla::dom::DestroyProtoOrIfaceCache;
 /***************************************************************************/
 // stuff used by all
 
-static nsresult ThrowAndFail(unsigned errNum, JSContext* cx, bool* retval)
+static nsresult ThrowAndFail(nsresult errNum, JSContext* cx, bool* retval)
 {
     XPCThrower::Throw(errNum, cx);
     *retval = false;
diff --git a/js/xpconnect/src/XPCException.cpp b/js/xpconnect/src/XPCException.cpp
index 12eb2ddf7dd8..f6a55a44b555 100644
--- a/js/xpconnect/src/XPCException.cpp
+++ b/js/xpconnect/src/XPCException.cpp
@@ -27,7 +27,7 @@ static struct ResultMap
     {(val), #val, format},
 #include "xpc.msg"
 #undef XPC_MSG_DEF
-    {0,0,0}   // sentinel to mark end of array
+    {NS_OK,0,0}   // sentinel to mark end of array
 };
 
 #define RESULT_COUNT ((sizeof(map) / sizeof(map[0]))-1)
@@ -100,7 +100,7 @@ NS_IMPL_CI_INTERFACE_GETTER1(nsXPCException, nsIXPCException)
 
 nsXPCException::nsXPCException()
     : mMessage(nullptr),
-      mResult(0),
+      mResult(NS_OK),
       mName(nullptr),
       mLocation(nullptr),
       mData(nullptr),
diff --git a/js/xpconnect/src/XPCWrappedNative.cpp b/js/xpconnect/src/XPCWrappedNative.cpp
index 473049f88ac8..17cbbf4b3913 100644
--- a/js/xpconnect/src/XPCWrappedNative.cpp
+++ b/js/xpconnect/src/XPCWrappedNative.cpp
@@ -2228,7 +2228,7 @@ XPCWrappedNative::GetSameCompartmentSecurityWrapper(JSContext *cx)
 
 /***************************************************************************/
 
-static JSBool Throw(unsigned errNum, XPCCallContext& ccx)
+static JSBool Throw(nsresult errNum, XPCCallContext& ccx)
 {
     XPCThrower::Throw(errNum, ccx);
     return false;
@@ -2676,7 +2676,7 @@ CallMethodHelper::QueryInterfaceFastPath() const
     }
 
     jsval v = JSVAL_NULL;
-    unsigned err;
+    nsresult err;
     JSBool success =
         XPCConvert::NativeData2JS(mCallContext, &v, &qiresult,
                                   nsXPTType::T_INTERFACE_IS,
@@ -2842,7 +2842,7 @@ CallMethodHelper::ConvertIndependentParam(uint8_t i)
         return false;
     }
 
-    unsigned err;
+    nsresult err;
     if (!XPCConvert::JSData2Native(mCallContext, &dp->val, src, type,
                                    true, &param_iid, &err)) {
         ThrowBadParam(err, i, mCallContext);
@@ -2940,7 +2940,7 @@ CallMethodHelper::ConvertDependentParam(uint8_t i)
         !GetInterfaceTypeFromParam(i, datum_type, &param_iid))
         return false;
 
-    unsigned err;
+    nsresult err;
 
     if (isArray || isSizedString) {
         if (!GetArraySizeFromParam(i, &array_count))
diff --git a/js/xpconnect/src/XPCWrappedNativeJSOps.cpp b/js/xpconnect/src/XPCWrappedNativeJSOps.cpp
index 61f53431fb9f..c6ca977d3033 100644
--- a/js/xpconnect/src/XPCWrappedNativeJSOps.cpp
+++ b/js/xpconnect/src/XPCWrappedNativeJSOps.cpp
@@ -17,7 +17,7 @@
 // All of the exceptions thrown into JS from this file go through here.
 // That makes this a nice place to set a breakpoint.
 
-static JSBool Throw(unsigned errNum, JSContext* cx)
+static JSBool Throw(nsresult errNum, JSContext* cx)
 {
     XPCThrower::Throw(errNum, cx);
     return false;
diff --git a/js/xpconnect/src/xpcprivate.h b/js/xpconnect/src/xpcprivate.h
index 0de9f6299084..fd5725f3b8b6 100644
--- a/js/xpconnect/src/xpcprivate.h
+++ b/js/xpconnect/src/xpcprivate.h
@@ -3394,7 +3394,7 @@ public:
 
     static JSBool JSStringWithSize2Native(XPCCallContext& ccx, void* d, jsval s,
                                           uint32_t count, const nsXPTType& type,
-                                          unsigned* pErr);
+                                          nsresult* pErr);
 
     static nsresult JSValToXPCException(XPCCallContext& ccx,
                                         jsval s,
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 023478085810..fc8b7964f873 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -1557,7 +1557,7 @@ nsCSSFrameConstructor::CreateGeneratedContent(nsFrameConstructorState& aState,
       if (-1 != barIndex) {
         nsAutoString  nameSpaceVal;
         contentString.Left(nameSpaceVal, barIndex);
-        PRInt32 error;
+        nsresult error;
         attrNameSpace = nameSpaceVal.ToInteger(&error, 10);
         contentString.Cut(0, barIndex + 1);
         if (contentString.Length()) {
diff --git a/layout/forms/nsListControlFrame.cpp b/layout/forms/nsListControlFrame.cpp
index e619752ec585..6dede73274e7 100644
--- a/layout/forms/nsListControlFrame.cpp
+++ b/layout/forms/nsListControlFrame.cpp
@@ -1572,7 +1572,7 @@ nsListControlFrame::GetFormProperty(nsIAtom* aName, nsAString& aValue) const
   // Get the selected value of option from local cache (optimization vs. widget)
   if (nsGkAtoms::selected == aName) {
     nsAutoString val(aValue);
-    PRInt32 error = 0;
+    nsresult error = NS_OK;
     bool selected = false;
     PRInt32 indx = val.ToInteger(&error, 10); // Get index from aValue
     if (error == 0)
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index 07a5352aff89..1a83ec9de3bf 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -3955,7 +3955,7 @@ nsGfxScrollFrameInner::GetCoordAttribute(nsIBox* aBox, nsIAtom* aAtom,
     content->GetAttr(kNameSpaceID_None, aAtom, value);
     if (!value.IsEmpty())
     {
-      PRInt32 error;
+      nsresult error;
       // convert it to appunits
       nscoord result = nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error));
       nscoord halfPixel = nsPresContext::CSSPixelsToAppUnits(0.5f);
diff --git a/layout/generic/nsTextFrameThebes.cpp b/layout/generic/nsTextFrameThebes.cpp
index f1df9805ba90..6748fe4ff75f 100644
--- a/layout/generic/nsTextFrameThebes.cpp
+++ b/layout/generic/nsTextFrameThebes.cpp
@@ -4140,7 +4140,8 @@ nsTextFrame::GetCursor(const nsPoint& aPoint,
         nsAutoString tabIndexStr;
         ancestorContent->GetAttr(kNameSpaceID_None, nsGkAtoms::tabindex, tabIndexStr);
         if (!tabIndexStr.IsEmpty()) {
-          PRInt32 rv, tabIndexVal = tabIndexStr.ToInteger(&rv);
+          nsresult rv;
+          PRInt32 tabIndexVal = tabIndexStr.ToInteger(&rv);
           if (NS_SUCCEEDED(rv) && tabIndexVal >= 0) {
             aCursor.mCursor = NS_STYLE_CURSOR_DEFAULT;
             break;
diff --git a/layout/mathml/nsMathMLOperators.cpp b/layout/mathml/nsMathMLOperators.cpp
index 4caecc483333..de6b388d5835 100644
--- a/layout/mathml/nsMathMLOperators.cpp
+++ b/layout/mathml/nsMathMLOperators.cpp
@@ -114,7 +114,7 @@ SetProperty(OperatorData* aOperatorData,
     else return;  // input is not applicable
 
     // aValue is assumed to be a digit from 0 to 7
-    PRInt32 error = 0;
+    nsresult error = NS_OK;
     float space = aValue.ToFloat(&error) / 18.0;
     if (error) return;
 
diff --git a/layout/mathml/nsMathMLmactionFrame.cpp b/layout/mathml/nsMathMLmactionFrame.cpp
index fe794ce014ed..e73a99c0d887 100644
--- a/layout/mathml/nsMathMLmactionFrame.cpp
+++ b/layout/mathml/nsMathMLmactionFrame.cpp
@@ -170,7 +170,7 @@ nsMathMLmactionFrame::GetSelectedFrame()
   GetAttribute(mContent, mPresentationData.mstyle, nsGkAtoms::selection_,
                value);
   if (!value.IsEmpty()) {
-    PRInt32 errorCode;
+    nsresult errorCode;
     selection = value.ToInteger(&errorCode);
     if (NS_FAILED(errorCode)) 
       selection = 1;
diff --git a/layout/mathml/nsMathMLmpaddedFrame.cpp b/layout/mathml/nsMathMLmpaddedFrame.cpp
index 6c4083492c2b..41a061195659 100644
--- a/layout/mathml/nsMathMLmpaddedFrame.cpp
+++ b/layout/mathml/nsMathMLmpaddedFrame.cpp
@@ -182,7 +182,7 @@ nsMathMLmpaddedFrame::ParseAttribute(nsString&   aString,
     return false;
   }
 
-  PRInt32 errorCode;
+  nsresult errorCode;
   float floatValue = number.ToFloat(&errorCode);
   if (errorCode) {
     aSign = NS_MATHML_SIGN_INVALID;
diff --git a/layout/mathml/nsMathMLmtableFrame.cpp b/layout/mathml/nsMathMLmtableFrame.cpp
index 2054e5ea0834..47cf78dff6c0 100644
--- a/layout/mathml/nsMathMLmtableFrame.cpp
+++ b/layout/mathml/nsMathMLmtableFrame.cpp
@@ -320,7 +320,7 @@ ParseAlignAttribute(nsString& aValue, eAlign& aAlign, PRInt32& aRowIndex)
     aAlign = eAlign_axis;
   }
   if (len) {
-    PRInt32 error;
+    nsresult error;
     aValue.Cut(0, len); // aValue is not a const here
     aRowIndex = aValue.ToInteger(&error);
     if (error)
@@ -775,7 +775,7 @@ nsMathMLmtdFrame::GetRowSpan()
     nsAutoString value;
     mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::rowspan, value);
     if (!value.IsEmpty()) {
-      PRInt32 error;
+      nsresult error;
       rowspan = value.ToInteger(&error);
       if (error || rowspan < 0)
         rowspan = 1;
@@ -795,7 +795,7 @@ nsMathMLmtdFrame::GetColSpan()
     nsAutoString value;
     mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::columnspan_, value);
     if (!value.IsEmpty()) {
-      PRInt32 error;
+      nsresult error;
       colspan = value.ToInteger(&error);
       if (error || colspan < 0 || colspan > MAX_COLSPAN)
         colspan = 1;
diff --git a/layout/printing/nsPrintData.cpp b/layout/printing/nsPrintData.cpp
index 000a3d4d72db..f69faafe7860 100644
--- a/layout/printing/nsPrintData.cpp
+++ b/layout/printing/nsPrintData.cpp
@@ -123,7 +123,7 @@ nsPrintData::DoOnProgressChange(PRInt32      aProgress,
     nsIWebProgressListener* wpl = mPrintProgressListeners.ObjectAt(i);
     wpl->OnProgressChange(nullptr, nullptr, aProgress, aMaxProgress, aProgress, aMaxProgress);
     if (aDoStartStop) {
-      wpl->OnStateChange(nullptr, nullptr, aFlag, 0);
+      wpl->OnStateChange(nullptr, nullptr, aFlag, NS_OK);
     }
   }
 }
diff --git a/layout/style/nsFontFaceLoader.h b/layout/style/nsFontFaceLoader.h
index 4bb29bddb8ec..db20b0931be5 100644
--- a/layout/style/nsFontFaceLoader.h
+++ b/layout/style/nsFontFaceLoader.h
@@ -72,7 +72,7 @@ protected:
   virtual nsresult LogMessage(gfxProxyFontEntry *aProxy,
                               const char *aMessage,
                               PRUint32 aFlags = nsIScriptError::errorFlag,
-                              nsresult aStatus = 0);
+                              nsresult aStatus = NS_OK);
 
   nsresult CheckFontLoad(gfxProxyFontEntry *aFontToLoad,
                          const gfxFontFaceSrc *aFontFaceSrc,
diff --git a/layout/svg/base/src/nsSVGImageFrame.cpp b/layout/svg/base/src/nsSVGImageFrame.cpp
index cc466d254b35..38850f2a2616 100644
--- a/layout/svg/base/src/nsSVGImageFrame.cpp
+++ b/layout/svg/base/src/nsSVGImageFrame.cpp
@@ -370,7 +370,7 @@ nsSVGImageFrame::PaintSVG(nsRenderingContext *aContext,
         static_cast<nsSVGSVGElement*>(imgRootFrame->GetContent());
       if (!rootSVGElem || !rootSVGElem->IsSVG(nsGkAtoms::svg)) {
         NS_ABORT_IF_FALSE(false, "missing or non-<svg> root node!!");
-        return false;
+        return NS_OK;
       }
 
       // Override preserveAspectRatio in our helper document
diff --git a/layout/xul/base/src/nsBox.cpp b/layout/xul/base/src/nsBox.cpp
index a14e8528e4ee..b5256cfe8a4a 100644
--- a/layout/xul/base/src/nsBox.cpp
+++ b/layout/xul/base/src/nsBox.cpp
@@ -470,7 +470,7 @@ nsIFrame::GetOrdinal(nsBoxLayoutState& aState)
   // When present, attribute value overrides CSS.
   nsIContent* content = GetContent();
   if (content && content->IsXUL()) {
-    PRInt32 error;
+    nsresult error;
     nsAutoString value;
 
     content->GetAttr(kNameSpaceID_None, nsGkAtoms::ordinal, value);
@@ -651,7 +651,7 @@ nsIBox::AddCSSPrefSize(nsIBox* aBox, nsSize& aSize, bool &aWidthSet, bool &aHeig
     // <select>
     if (content && content->IsXUL()) {
         nsAutoString value;
-        PRInt32 error;
+        nsresult error;
 
         content->GetAttr(kNameSpaceID_None, nsGkAtoms::width, value);
         if (!value.IsEmpty()) {
@@ -755,7 +755,7 @@ nsIBox::AddCSSMinSize(nsBoxLayoutState& aState, nsIBox* aBox, nsSize& aSize,
     nsIContent* content = aBox->GetContent();
     if (content && content->IsXUL()) {
         nsAutoString value;
-        PRInt32 error;
+        nsresult error;
 
         content->GetAttr(kNameSpaceID_None, nsGkAtoms::minwidth, value);
         if (!value.IsEmpty())
@@ -818,7 +818,7 @@ nsIBox::AddCSSMaxSize(nsIBox* aBox, nsSize& aSize, bool &aWidthSet, bool &aHeigh
     nsIContent* content = aBox->GetContent();
     if (content && content->IsXUL()) {
         nsAutoString value;
-        PRInt32 error;
+        nsresult error;
 
         content->GetAttr(kNameSpaceID_None, nsGkAtoms::maxwidth, value);
         if (!value.IsEmpty()) {
@@ -856,7 +856,7 @@ nsIBox::AddCSSFlex(nsBoxLayoutState& aState, nsIBox* aBox, nscoord& aFlex)
     // attribute value overrides CSS
     nsIContent* content = aBox->GetContent();
     if (content && content->IsXUL()) {
-        PRInt32 error;
+        nsresult error;
         nsAutoString value;
 
         content->GetAttr(kNameSpaceID_None, nsGkAtoms::flex, value);
diff --git a/layout/xul/base/src/nsDeckFrame.cpp b/layout/xul/base/src/nsDeckFrame.cpp
index 9a3a4ae57fa8..8a25fce487b5 100644
--- a/layout/xul/base/src/nsDeckFrame.cpp
+++ b/layout/xul/base/src/nsDeckFrame.cpp
@@ -117,7 +117,7 @@ nsDeckFrame::GetSelectedIndex()
   nsAutoString value;
   if (mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::selectedIndex, value))
   {
-    PRInt32 error;
+    nsresult error;
 
     // convert it to an integer
     index = value.ToInteger(&error);
diff --git a/layout/xul/base/src/nsListBoxBodyFrame.cpp b/layout/xul/base/src/nsListBoxBodyFrame.cpp
index c884c9c08a8c..2adfcfc0df7b 100644
--- a/layout/xul/base/src/nsListBoxBodyFrame.cpp
+++ b/layout/xul/base/src/nsListBoxBodyFrame.cpp
@@ -601,7 +601,7 @@ nsListBoxBodyFrame::GetRowCount()
 PRInt32
 nsListBoxBodyFrame::GetFixedRowSize()
 {
-  PRInt32 dummy;
+  nsresult dummy;
 
   nsAutoString rows;
   mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::rows, rows);
diff --git a/layout/xul/base/src/nsMenuPopupFrame.cpp b/layout/xul/base/src/nsMenuPopupFrame.cpp
index c52fcee14be5..7d2dbe1dd21f 100644
--- a/layout/xul/base/src/nsMenuPopupFrame.cpp
+++ b/layout/xul/base/src/nsMenuPopupFrame.cpp
@@ -629,7 +629,7 @@ nsMenuPopupFrame::InitializePopup(nsIContent* aAnchorContent,
     mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::left, left);
     mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::top, top);
 
-    PRInt32 err;
+    nsresult err;
     if (!left.IsEmpty()) {
       PRInt32 x = left.ToInteger(&err);
       if (NS_SUCCEEDED(err))
@@ -1791,7 +1791,7 @@ nsMenuPopupFrame::MoveToAttributePosition()
   nsAutoString left, top;
   mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::left, left);
   mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::top, top);
-  PRInt32 err1, err2;
+  nsresult err1, err2;
   PRInt32 xpos = left.ToInteger(&err1);
   PRInt32 ypos = top.ToInteger(&err2);
 
diff --git a/layout/xul/base/src/nsSliderFrame.cpp b/layout/xul/base/src/nsSliderFrame.cpp
index bb977f934679..56a0f2ee9caa 100644
--- a/layout/xul/base/src/nsSliderFrame.cpp
+++ b/layout/xul/base/src/nsSliderFrame.cpp
@@ -171,7 +171,7 @@ nsSliderFrame::GetIntegerAttribute(nsIContent* content, nsIAtom* atom, PRInt32 d
     nsAutoString value;
     content->GetAttr(kNameSpaceID_None, atom, value);
     if (!value.IsEmpty()) {
-      PRInt32 error;
+      nsresult error;
 
       // convert it to an integer
       defaultValue = value.ToInteger(&error);
diff --git a/layout/xul/base/src/nsStackLayout.cpp b/layout/xul/base/src/nsStackLayout.cpp
index 37ae3e2bf46b..12e4e9d8188f 100644
--- a/layout/xul/base/src/nsStackLayout.cpp
+++ b/layout/xul/base/src/nsStackLayout.cpp
@@ -178,7 +178,7 @@ nsStackLayout::GetOffset(nsBoxLayoutState& aState, nsIBox* aChild, nsMargin& aOf
   if (content) {
     bool ltr = aChild->GetStyleVisibility()->mDirection == NS_STYLE_DIRECTION_LTR;
     nsAutoString value;
-    PRInt32 error;
+    nsresult error;
 
     content->GetAttr(kNameSpaceID_None, nsGkAtoms::start, value);
     if (!value.IsEmpty()) {
diff --git a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
index 40074d74b06c..4940fa5faa10 100644
--- a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
@@ -190,7 +190,7 @@ nsTreeBodyFrame::GetMinSize(nsBoxLayoutState& aBoxLayoutState)
     nsAutoString size;
     baseElement->GetAttr(kNameSpaceID_None, nsGkAtoms::size, size);
     if (!size.IsEmpty()) {
-      PRInt32 err;
+      nsresult err;
       desiredRows = size.ToInteger(&err);
       mHasFixedRowCount = true;
       mPageLength = desiredRows;
@@ -204,7 +204,7 @@ nsTreeBodyFrame::GetMinSize(nsBoxLayoutState& aBoxLayoutState)
     nsAutoString rows;
     baseElement->GetAttr(kNameSpaceID_None, nsGkAtoms::rows, rows);
     if (!rows.IsEmpty()) {
-      PRInt32 err;
+      nsresult err;
       desiredRows = rows.ToInteger(&err);
       mPageLength = desiredRows;
     }
@@ -355,7 +355,7 @@ nsTreeBodyFrame::EnsureView()
         box->GetProperty(NS_LITERAL_STRING("topRow").get(),
                          getter_Copies(rowStr));
         nsAutoString rowStr2(rowStr);
-        PRInt32 error;
+        nsresult error;
         PRInt32 rowIndex = rowStr2.ToInteger(&error);
 
         // Set our view.
@@ -3719,7 +3719,7 @@ nsTreeBodyFrame::PaintProgressMeter(PRInt32              aRowIndex,
     nsAutoString value;
     mView->GetCellValue(aRowIndex, aColumn, value);
 
-    PRInt32 rv;
+    nsresult rv;
     PRInt32 intValue = value.ToInteger(&rv);
     if (intValue < 0)
       intValue = 0;
diff --git a/modules/libjar/nsZipArchive.cpp b/modules/libjar/nsZipArchive.cpp
index 1f10c779e434..1f822323654e 100644
--- a/modules/libjar/nsZipArchive.cpp
+++ b/modules/libjar/nsZipArchive.cpp
@@ -375,7 +375,7 @@ nsresult nsZipArchive::ExtractFile(nsZipItem *item, const char *outname,
 //---------------------------------------------
 // nsZipArchive::FindInit
 //---------------------------------------------
-PRInt32
+nsresult
 nsZipArchive::FindInit(const char * aPattern, nsZipFind **aFind)
 {
   if (!aFind)
diff --git a/modules/libjar/nsZipArchive.h b/modules/libjar/nsZipArchive.h
index 7505b0d9ac40..0bbf1d0ea340 100644
--- a/modules/libjar/nsZipArchive.h
+++ b/modules/libjar/nsZipArchive.h
@@ -173,7 +173,7 @@ public:
    *                      will be set to NULL.
    * @return  status code
    */
-  PRInt32 FindInit(const char * aPattern, nsZipFind** aFind);
+  nsresult FindInit(const char * aPattern, nsZipFind** aFind);
 
   /*
    * Gets an undependent handle to the mapped file.
diff --git a/netwerk/base/src/nsChannelClassifier.cpp b/netwerk/base/src/nsChannelClassifier.cpp
index c02767bbad33..4a2e6db23d36 100644
--- a/netwerk/base/src/nsChannelClassifier.cpp
+++ b/netwerk/base/src/nsChannelClassifier.cpp
@@ -36,7 +36,7 @@ nsChannelClassifier::Start(nsIChannel *aChannel)
 {
     // Don't bother to run the classifier on a load that has already failed.
     // (this might happen after a redirect)
-    PRUint32 status;
+    nsresult status;
     aChannel->GetStatus(&status);
     if (NS_FAILED(status))
         return NS_OK;
diff --git a/netwerk/base/src/nsIOService.cpp b/netwerk/base/src/nsIOService.cpp
index dbd6af29f6f2..9a2a82218472 100644
--- a/netwerk/base/src/nsIOService.cpp
+++ b/netwerk/base/src/nsIOService.cpp
@@ -906,7 +906,7 @@ nsIOService::ParsePortList(nsIPrefBranch *prefBranch, const char *pref, bool rem
         PRUint32 index;
         for (index=0; index < portListArray.Length(); index++) {
             portListArray[index].StripWhitespace();
-            PRInt32 aErrorCode, portBegin, portEnd;
+            PRInt32 portBegin, portEnd;
 
             if (PR_sscanf(portListArray[index].get(), "%d-%d", &portBegin, &portEnd) == 2) {
                if ((portBegin < 65536) && (portEnd < 65536)) {
@@ -920,6 +920,7 @@ nsIOService::ParsePortList(nsIPrefBranch *prefBranch, const char *pref, bool rem
                    }
                }
             } else {
+               nsresult aErrorCode;
                PRInt32 port = portListArray[index].ToInteger(&aErrorCode);
                if (NS_SUCCEEDED(aErrorCode) && port < 65536) {
                    if (remove)
diff --git a/netwerk/base/src/nsURLParsers.cpp b/netwerk/base/src/nsURLParsers.cpp
index dbb09f52da76..ea81cbeb5e2a 100644
--- a/netwerk/base/src/nsURLParsers.cpp
+++ b/netwerk/base/src/nsURLParsers.cpp
@@ -581,7 +581,7 @@ nsAuthURLParser::ParseServerInfo(const char *serverinfo, PRInt32 serverinfoLen,
                 if (nondigit && *nondigit)
                     return NS_ERROR_MALFORMED_URI;
 
-                PRInt32 err;
+                nsresult err;
                 *port = buf.ToInteger(&err);
                 if (NS_FAILED(err) || *port <= 0)
                     return NS_ERROR_MALFORMED_URI;
diff --git a/netwerk/protocol/ftp/nsFtpConnectionThread.cpp b/netwerk/protocol/ftp/nsFtpConnectionThread.cpp
index 8c9cffc20dce..aa8ec5541e3c 100644
--- a/netwerk/protocol/ftp/nsFtpConnectionThread.cpp
+++ b/netwerk/protocol/ftp/nsFtpConnectionThread.cpp
@@ -1024,7 +1024,7 @@ nsFtpState::R_mdtm() {
 
             // Save lastModified time for downloaded files.
             nsCAutoString timeString;
-            PRInt32 error;
+            nsresult error;
             PRExplodedTime exTime;
 
             mResponseMsg.Mid(timeString, 0, 4);
@@ -2188,7 +2188,7 @@ nsFtpState::ReadCacheEntry()
     nsXPIDLCString serverType;
     mCacheEntry->GetMetaDataElement("servertype", getter_Copies(serverType));
     nsCAutoString serverNum(serverType.get());
-    PRInt32 err;
+    nsresult err;
     mServerType = serverNum.ToInteger(&err);
     
     mChannel->PushStreamConverter("text/ftp-dir",
diff --git a/netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp b/netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp
index 9f86830ca7ba..96cba8ce841c 100644
--- a/netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp
+++ b/netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp
@@ -530,8 +530,7 @@ nsWyciwygChannel::GetCharsetAndSource(PRInt32* aSource, nsACString& aCharset)
   mCacheEntry->GetMetaDataElement("charset-source", getter_Copies(sourceStr));
 
   PRInt32 source;
-  // XXXbz ToInteger takes an PRInt32* but outputs an nsresult in it... :(
-  PRInt32 err;
+  nsresult err;
   source = sourceStr.ToInteger(&err);
   if (NS_FAILED(err) || source == 0) {
     return NS_ERROR_NOT_AVAILABLE;
diff --git a/netwerk/test/urltest.cpp b/netwerk/test/urltest.cpp
index b68e2b253bf2..349be30395b3 100644
--- a/netwerk/test/urltest.cpp
+++ b/netwerk/test/urltest.cpp
@@ -128,7 +128,7 @@ nsresult writeout(const char* i_pURL, PRInt32 urlFactory = URL_FACTORY_DEFAULT)
 {
     if (!i_pURL) return NS_ERROR_FAILURE;
     nsCString temp;
-    int rv = writeoutto(i_pURL, getter_Copies(temp), urlFactory);
+    nsresult rv = writeoutto(i_pURL, getter_Copies(temp), urlFactory);
     printf("%s\n%s\n", i_pURL, temp.get());
     return rv;
 }
@@ -248,7 +248,7 @@ nsresult makeAbsTest(const char* i_BaseURI, const char* relativePortion,
     return NS_OK;
 }
 
-int doMakeAbsTest(const char* i_URL = 0, const char* i_relativePortion=0)
+nsresult doMakeAbsTest(const char* i_URL = 0, const char* i_relativePortion=0)
 {
     if (i_URL && i_relativePortion)
     {
diff --git a/parser/htmlparser/src/nsHTMLTokens.cpp b/parser/htmlparser/src/nsHTMLTokens.cpp
index 1284246b92b2..42a198e90433 100644
--- a/parser/htmlparser/src/nsHTMLTokens.cpp
+++ b/parser/htmlparser/src/nsHTMLTokens.cpp
@@ -87,7 +87,7 @@ ConsumeEntity(nsScannerSharedSubstring& aString,
           writable.Append(amp);
           result = NS_OK;
         } else {
-          PRInt32 err;
+          nsresult err;
           theNCRValue = entity.ToInteger(&err, kAutoDetect);
           AppendNCR(writable, theNCRValue);
         }
@@ -1453,7 +1453,7 @@ CCommentToken::ConsumeQuirksComment(nsScanner& aScanner)
 nsresult
 CCommentToken::Consume(PRUnichar aChar, nsScanner& aScanner, PRInt32 aFlag)
 {
-  nsresult result = true;
+  nsresult result = NS_OK;
 
   if (aFlag & NS_IPARSER_FLAG_STRICT_MODE) {
     // Enabling strict comment parsing for Bug 53011 and 2749 contradicts!
@@ -2165,7 +2165,7 @@ CEntityToken::TranslateToUnicodeStr(nsString& aString)
     PRUnichar theChar0 = mTextValue.CharAt(0);
 
     if (kHashsign == theChar0) {
-      PRInt32 err = 0;
+      nsresult err = NS_OK;
 
       value = mTextValue.ToInteger(&err, kAutoDetect);
 
diff --git a/parser/htmlparser/src/nsParser.cpp b/parser/htmlparser/src/nsParser.cpp
index 63a5124d5f67..e27d71230cc0 100644
--- a/parser/htmlparser/src/nsParser.cpp
+++ b/parser/htmlparser/src/nsParser.cpp
@@ -198,7 +198,7 @@ nsParser::Initialize(bool aConstructor)
   mCharsetSource = kCharsetUninitialized;
   mCharset.AssignLiteral("ISO-8859-1");
   mInternalState = NS_OK;
-  mStreamStatus = 0;
+  mStreamStatus = NS_OK;
   mCommand = eViewNormal;
   mFlags = NS_PARSER_FLAG_OBSERVERS_ENABLED |
            NS_PARSER_FLAG_PARSER_ENABLED |
diff --git a/parser/htmlparser/src/nsParser.h b/parser/htmlparser/src/nsParser.h
index 3567a09751ed..8d25ac1ddc8e 100644
--- a/parser/htmlparser/src/nsParser.h
+++ b/parser/htmlparser/src/nsParser.h
@@ -412,7 +412,7 @@ protected:
     
     eParserCommands     mCommand;
     nsresult            mInternalState;
-    PRInt32             mStreamStatus;
+    nsresult            mStreamStatus;
     PRInt32             mCharsetSource;
     
     PRUint16            mFlags;
diff --git a/rdf/base/src/nsContainerEnumerator.cpp b/rdf/base/src/nsContainerEnumerator.cpp
index 2e74abcfe1a0..552ff1dda307 100644
--- a/rdf/base/src/nsContainerEnumerator.cpp
+++ b/rdf/base/src/nsContainerEnumerator.cpp
@@ -159,7 +159,7 @@ ContainerEnumeratorImpl::HasMoreElements(bool* aResult)
          const PRUnichar *nextValStr;
          nextValLiteral->GetValueConst(&nextValStr);
 		 
-         PRInt32 err;
+         nsresult err;
          PRInt32 nextVal = nsAutoString(nextValStr).ToInteger(&err);
 
          if (nextVal > max)
diff --git a/rdf/base/src/nsRDFContainer.cpp b/rdf/base/src/nsRDFContainer.cpp
index b3cfcb2915be..5f996ebfa669 100644
--- a/rdf/base/src/nsRDFContainer.cpp
+++ b/rdf/base/src/nsRDFContainer.cpp
@@ -184,7 +184,7 @@ RDFContainerImpl::GetCount(PRInt32 *aCount)
     nsAutoString nextValStr(s);
 
     PRInt32 nextVal;
-    PRInt32 err;
+    nsresult err;
     nextVal = nextValStr.ToInteger(&err);
     if (NS_FAILED(err))
         return NS_ERROR_UNEXPECTED;
diff --git a/rdf/base/src/nsRDFContentSink.cpp b/rdf/base/src/nsRDFContentSink.cpp
index 30b1de2aa2af..4cea6b990a6e 100644
--- a/rdf/base/src/nsRDFContentSink.cpp
+++ b/rdf/base/src/nsRDFContentSink.cpp
@@ -696,8 +696,8 @@ RDFContentSinkImpl::ParseText(nsIRDFNode **aResult)
 
     case eRDFContentSinkParseMode_Int:
         {
-            PRInt32 i, err;
-            i = value.ToInteger(&err);
+            nsresult err;
+            PRInt32 i = value.ToInteger(&err);
             nsIRDFInt *result;
             gRDFService->GetIntLiteral(i, &result);
             *aResult = result;
diff --git a/rdf/datasource/src/nsFileSystemDataSource.cpp b/rdf/datasource/src/nsFileSystemDataSource.cpp
index 15ed8cc34e46..b29a80d4ab8f 100644
--- a/rdf/datasource/src/nsFileSystemDataSource.cpp
+++ b/rdf/datasource/src/nsFileSystemDataSource.cpp
@@ -1014,7 +1014,7 @@ FileSystemDataSource::GetFolderList(nsIRDFResource *source, bool allowHidden,
 
     nsCOMPtr<nsIFileURL>    fileURL = do_QueryInterface(aIURI);
     if (!fileURL)
-        return(false);
+        return NS_OK;
 
     nsCOMPtr<nsIFile>   aDir;
     if (NS_FAILED(rv = fileURL->GetFile(getter_AddRefs(aDir))))
@@ -1122,7 +1122,7 @@ FileSystemDataSource::GetLastMod(nsIRDFResource *source, nsIRDFDate **aResult)
 
     nsCOMPtr<nsIFileURL>    fileURL = do_QueryInterface(aIURI);
     if (!fileURL)
-        return(false);
+        return NS_OK;
 
     nsCOMPtr<nsIFile>   aFile;
     if (NS_FAILED(rv = fileURL->GetFile(getter_AddRefs(aFile))))
@@ -1169,7 +1169,7 @@ FileSystemDataSource::GetFileSize(nsIRDFResource *source, nsIRDFInt **aResult)
 
     nsCOMPtr<nsIFileURL>    fileURL = do_QueryInterface(aIURI);
     if (!fileURL)
-        return(false);
+        return NS_OK;
 
     nsCOMPtr<nsIFile>   aFile;
     if (NS_FAILED(rv = fileURL->GetFile(getter_AddRefs(aFile))))
@@ -1220,7 +1220,7 @@ FileSystemDataSource::GetName(nsIRDFResource *source, nsIRDFLiteral **aResult)
 
     nsCOMPtr<nsIFileURL>    fileURL = do_QueryInterface(aIURI);
     if (!fileURL)
-        return(false);
+        return NS_OK;
 
     nsCOMPtr<nsIFile>   aFile;
     if (NS_FAILED(rv = fileURL->GetFile(getter_AddRefs(aFile))))
diff --git a/security/manager/ssl/src/nsCertOverrideService.cpp b/security/manager/ssl/src/nsCertOverrideService.cpp
index 86c72a34ecce..5fb94621bd30 100644
--- a/security/manager/ssl/src/nsCertOverrideService.cpp
+++ b/security/manager/ssl/src/nsCertOverrideService.cpp
@@ -272,7 +272,7 @@ nsCertOverrideService::Read()
     if (portIndex == kNotFound)
       continue; // Ignore broken entries
 
-    PRInt32 portParseError;
+    nsresult portParseError;
     nsCAutoString portString(Substring(host, portIndex+1));
     port = portString.ToInteger(&portParseError);
     if (portParseError)
diff --git a/security/manager/ssl/src/nsCertVerificationThread.cpp b/security/manager/ssl/src/nsCertVerificationThread.cpp
index 4317c1841e44..8833e1d8d5d3 100644
--- a/security/manager/ssl/src/nsCertVerificationThread.cpp
+++ b/security/manager/ssl/src/nsCertVerificationThread.cpp
@@ -159,7 +159,7 @@ void nsCertVerificationThread::Run(void)
 }
 
 nsCertVerificationResult::nsCertVerificationResult()
-: mRV(0),
+: mRV(NS_OK),
   mVerified(0),
   mCount(0),
   mUsages(0)
diff --git a/storage/test/test_deadlock_detector.cpp b/storage/test/test_deadlock_detector.cpp
index f0c28120073f..78e6e1016416 100644
--- a/storage/test/test_deadlock_detector.cpp
+++ b/storage/test/test_deadlock_detector.cpp
@@ -299,7 +299,7 @@ Sanity_Child()
     TestMutex m1("dd.sanity.m1");
     m1.Lock();
     m1.Lock();
-    return 0;                  // not reached
+    return NS_OK;                  // not reached
 }
 
 nsresult
@@ -329,7 +329,7 @@ Sanity2_Child()
     m1.Lock();
     m2.Lock();
     m1.Lock();
-    return 0;                  // not reached
+    return NS_OK;                  // not reached
 }
 
 nsresult
@@ -371,7 +371,7 @@ Sanity3_Child()
 
     m4.Lock();
     m1.Lock();
-    return 0;
+    return NS_OK;
 }
 
 nsresult
@@ -403,7 +403,7 @@ Sanity4_Child()
     m1.Enter();
     m2.Lock();
     m1.Enter();
-    return 0;
+    return NS_OK;
 }
 
 nsresult
@@ -463,7 +463,7 @@ TwoThreads_Child()
     PRThread* t2 = spawn(TwoThreads_thread, (void*) 1);
     PR_JoinThread(t2);
 
-    return 0;
+    return NS_OK;
 }
 
 nsresult
@@ -522,7 +522,7 @@ ContentionNoDeadlock_Child()
     for (PRUint32 i = 0; i < ArrayLength(cndMs); ++i)
         delete cndMs[i];
 
-    return 0;
+    return NS_OK;
 }
 
 nsresult
diff --git a/toolkit/components/downloads/nsDownloadProxy.h b/toolkit/components/downloads/nsDownloadProxy.h
index acd9caa56cac..38809453bdc9 100644
--- a/toolkit/components/downloads/nsDownloadProxy.h
+++ b/toolkit/components/downloads/nsDownloadProxy.h
@@ -75,7 +75,7 @@ public:
 
   NS_IMETHODIMP OnStateChange(nsIWebProgress* aWebProgress,
                               nsIRequest* aRequest, PRUint32 aStateFlags,
-                              PRUint32 aStatus)
+                              nsresult aStatus)
   {
     NS_ENSURE_TRUE(mInner, NS_ERROR_NOT_INITIALIZED);
     return mInner->OnStateChange(aWebProgress, aRequest, aStateFlags, aStatus);
diff --git a/toolkit/components/places/nsNavHistoryQuery.cpp b/toolkit/components/places/nsNavHistoryQuery.cpp
index 8c224c4ae012..88fee3b0dcab 100644
--- a/toolkit/components/places/nsNavHistoryQuery.cpp
+++ b/toolkit/components/places/nsNavHistoryQuery.cpp
@@ -1658,7 +1658,7 @@ SetQueryKeyUint32(const nsCString& aValue, nsINavHistoryQuery* aQuery,
                   Uint32QuerySetter setter)
 {
   nsresult rv;
-  PRUint32 value = aValue.ToInteger(reinterpret_cast<PRInt32*>(&rv));
+  PRUint32 value = aValue.ToInteger(&rv);
   if (NS_SUCCEEDED(rv)) {
     rv = (aQuery->*setter)(value);
     if (NS_FAILED(rv)) {
@@ -1673,7 +1673,7 @@ SetOptionsKeyUint32(const nsCString& aValue, nsINavHistoryQueryOptions* aOptions
                   Uint32OptionsSetter setter)
 {
   nsresult rv;
-  PRUint32 value = aValue.ToInteger(reinterpret_cast<PRInt32*>(&rv));
+  PRUint32 value = aValue.ToInteger(&rv);
   if (NS_SUCCEEDED(rv)) {
     rv = (aOptions->*setter)(value);
     if (NS_FAILED(rv)) {
@@ -1689,8 +1689,7 @@ SetOptionsKeyUint16(const nsCString& aValue, nsINavHistoryQueryOptions* aOptions
                     Uint16OptionsSetter setter)
 {
   nsresult rv;
-  PRUint16 value = static_cast<PRUint16>
-                              (aValue.ToInteger(reinterpret_cast<PRInt32*>(&rv)));
+  PRUint16 value = static_cast<PRUint16>(aValue.ToInteger(&rv));
   if (NS_SUCCEEDED(rv)) {
     rv = (aOptions->*setter)(value);
     if (NS_FAILED(rv)) {
diff --git a/toolkit/components/places/nsNavHistoryResult.cpp b/toolkit/components/places/nsNavHistoryResult.cpp
index 70a55dfc5c53..808be1211ca8 100644
--- a/toolkit/components/places/nsNavHistoryResult.cpp
+++ b/toolkit/components/places/nsNavHistoryResult.cpp
@@ -4750,7 +4750,7 @@ nsNavHistoryResult::OnVisit(nsIURI* aURI, PRInt64 aVisitId, PRTime aTime,
       rv = firstChild->GetTitle(title);
       NS_ENSURE_SUCCESS(rv, rv);
       nsNavHistory* history = nsNavHistory::GetHistoryService();
-      NS_ENSURE_TRUE(history, 0);
+      NS_ENSURE_TRUE(history, NS_OK);
       nsCAutoString todayLabel;
       history->GetStringFromName(
         NS_LITERAL_STRING("finduri-AgeInDays-is-0").get(), todayLabel);
diff --git a/toolkit/components/url-classifier/nsUrlClassifierStreamUpdater.cpp b/toolkit/components/url-classifier/nsUrlClassifierStreamUpdater.cpp
index b49df9cd2875..c93d7b7a6210 100644
--- a/toolkit/components/url-classifier/nsUrlClassifierStreamUpdater.cpp
+++ b/toolkit/components/url-classifier/nsUrlClassifierStreamUpdater.cpp
@@ -327,7 +327,7 @@ nsUrlClassifierStreamUpdater::UpdateSuccess(PRUint32 requestedTimeout)
 }
 
 NS_IMETHODIMP
-nsUrlClassifierStreamUpdater::UpdateError(PRUint32 result)
+nsUrlClassifierStreamUpdater::UpdateError(nsresult result)
 {
   LOG(("nsUrlClassifierStreamUpdater::UpdateError [this=%p]", this));
 
@@ -408,10 +408,11 @@ nsUrlClassifierStreamUpdater::OnStartRequest(nsIRequest *request,
         // 404 or other error, pass error status back
         LOG(("HTTP request returned failure code."));
 
-        rv = httpChannel->GetResponseStatus(&status);
+        PRUint32 requestStatus;
+        rv = httpChannel->GetResponseStatus(&requestStatus);
         NS_ENSURE_SUCCESS(rv, rv);
 
-        strStatus.AppendInt(status);
+        strStatus.AppendInt(requestStatus);
         downloadError = true;
       }
     }
diff --git a/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp b/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp
index 7d612c196c7f..213f19ca00bc 100644
--- a/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp
+++ b/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp
@@ -122,7 +122,7 @@ IsInNoProxyList(const nsACString& aHost, PRInt32 aPort, const char* noProxyVal)
       ++colon;
       nsDependentCSubstring portStr(colon, last);
       nsCAutoString portStr2(portStr); // We need this for ToInteger. String API's suck.
-      PRInt32 err;
+      nsresult err;
       port = portStr2.ToInteger(&err);
       if (NS_FAILED(err)) {
         port = -2; // don't match any port, so we ignore this pattern
@@ -341,7 +341,7 @@ static bool HostIgnoredByProxy(const nsACString& aIgnore,
     ++slash;
     nsDependentCSubstring maskStr(slash, end);
     nsCAutoString maskStr2(maskStr);
-    PRInt32 err;
+    nsresult err;
     mask = maskStr2.ToInteger(&err);
     if (err != 0) {
       mask = 128;
diff --git a/widget/gtk2/nsDragService.cpp b/widget/gtk2/nsDragService.cpp
index 7ef1914324dd..6f176cefdb4b 100644
--- a/widget/gtk2/nsDragService.cpp
+++ b/widget/gtk2/nsDragService.cpp
@@ -1412,7 +1412,7 @@ CreateUriList(nsISupportsArray *items, gchar **text, gint *length)
         if (item) {
             PRUint32 tmpDataLen = 0;
             void    *tmpData = NULL;
-            nsresult rv = 0;
+            nsresult rv = NS_OK;
             nsCOMPtr<nsISupports> data;
             rv = item->GetTransferData(kURLMime,
                                        getter_AddRefs(data),
diff --git a/widget/xpwidgets/nsNativeTheme.cpp b/widget/xpwidgets/nsNativeTheme.cpp
index 6e5c277edaa5..3ab274c32d1b 100644
--- a/widget/xpwidgets/nsNativeTheme.cpp
+++ b/widget/xpwidgets/nsNativeTheme.cpp
@@ -128,7 +128,8 @@ nsNativeTheme::CheckIntAttr(nsIFrame* aFrame, nsIAtom* aAtom, PRInt32 defaultVal
 
   nsAutoString attr;
   aFrame->GetContent()->GetAttr(kNameSpaceID_None, aAtom, attr);
-  PRInt32 err, value = attr.ToInteger(&err);
+  nsresult err;
+  PRInt32 value = attr.ToInteger(&err);
   if (attr.IsEmpty() || NS_FAILED(err))
     return defaultValue;
 
diff --git a/widget/xpwidgets/nsPrintOptionsImpl.cpp b/widget/xpwidgets/nsPrintOptionsImpl.cpp
index c70d1e26ef9f..609f1ca33e8c 100644
--- a/widget/xpwidgets/nsPrintOptionsImpl.cpp
+++ b/widget/xpwidgets/nsPrintOptionsImpl.cpp
@@ -1088,7 +1088,7 @@ nsPrintOptions::ReadInchesToTwipsPref(const char * aPrefId, PRInt32& aTwips,
     rv = Preferences::GetString(aMarginPref, &str);
   }
   if (NS_SUCCEEDED(rv) && !str.IsEmpty()) {
-    PRInt32 errCode;
+    nsresult errCode;
     float inches = str.ToFloat(&errCode);
     if (NS_SUCCEEDED(errCode)) {
       aTwips = NS_INCHES_TO_INT_TWIPS(inches);
diff --git a/xpcom/string/public/nsTString.h b/xpcom/string/public/nsTString.h
index e462e44dd9b5..802a3cb06ef8 100644
--- a/xpcom/string/public/nsTString.h
+++ b/xpcom/string/public/nsTString.h
@@ -230,7 +230,7 @@ class nsTString_CharT : public nsTSubstring_CharT
          * @param   aErrorCode will contain error if one occurs
          * @return  double-precision float rep of string value
          */
-      double ToDouble( PRInt32* aErrorCode ) const;
+      double ToDouble( nsresult* aErrorCode ) const;
 
         /**
          * Perform string to single-precision float conversion.
@@ -238,7 +238,7 @@ class nsTString_CharT : public nsTSubstring_CharT
          * @param   aErrorCode will contain error if one occurs
          * @return  single-precision float rep of string value
          */
-      float ToFloat( PRInt32* aErrorCode ) const {
+      float ToFloat( nsresult* aErrorCode ) const {
         return (float)ToDouble(aErrorCode);
       }
 
@@ -249,10 +249,7 @@ class nsTString_CharT : public nsTSubstring_CharT
          * @param   aRadix tells us which radix to assume; kAutoDetect tells us to determine the radix for you.
          * @return  int rep of string value, and possible (out) error code
          */
-      PRInt32 ToInteger( PRInt32* aErrorCode, PRUint32 aRadix=kRadix10 ) const;
-      PRInt32 ToInteger( nsresult* aErrorCode, PRUint32 aRadix=kRadix10 ) const {
-        return ToInteger(reinterpret_cast<PRInt32*>(aErrorCode), aRadix);
-      }
+      PRInt32 ToInteger( nsresult* aErrorCode, PRUint32 aRadix=kRadix10 ) const;
 
         /**
          * |Left|, |Mid|, and |Right| are annoying signatures that seem better almost
diff --git a/xpcom/string/src/nsStringObsolete.cpp b/xpcom/string/src/nsStringObsolete.cpp
index 503d0dbb06d2..27ade880553b 100644
--- a/xpcom/string/src/nsStringObsolete.cpp
+++ b/xpcom/string/src/nsStringObsolete.cpp
@@ -984,7 +984,7 @@ nsString::EqualsIgnoreCase( const char* aString, PRInt32 aCount ) const
    */
 
 double
-nsCString::ToDouble(PRInt32* aErrorCode) const
+nsCString::ToDouble(nsresult* aErrorCode) const
   {
     double res = 0.0;
     if (mLength > 0)
@@ -994,20 +994,20 @@ nsCString::ToDouble(PRInt32* aErrorCode) const
         // Use PR_strtod, not strtod, since we don't want locale involved.
         res = PR_strtod(str, &conv_stopped);
         if (conv_stopped == str+mLength)
-          *aErrorCode = (PRInt32) NS_OK;
+          *aErrorCode = NS_OK;
         else // Not all the string was scanned
-          *aErrorCode = (PRInt32) NS_ERROR_ILLEGAL_VALUE;
+          *aErrorCode = NS_ERROR_ILLEGAL_VALUE;
       }
     else
       {
         // The string was too short (0 characters)
-        *aErrorCode = (PRInt32) NS_ERROR_ILLEGAL_VALUE;
+        *aErrorCode = NS_ERROR_ILLEGAL_VALUE;
       }
     return res;
   }
 
 double
-nsString::ToDouble(PRInt32* aErrorCode) const
+nsString::ToDouble(nsresult* aErrorCode) const
   {
     return NS_LossyConvertUTF16toASCII(*this).ToDouble(aErrorCode);
   }
diff --git a/xpcom/string/src/nsTStringObsolete.cpp b/xpcom/string/src/nsTStringObsolete.cpp
index f02e2783f788..2fe3bbb2d816 100644
--- a/xpcom/string/src/nsTStringObsolete.cpp
+++ b/xpcom/string/src/nsTStringObsolete.cpp
@@ -109,7 +109,7 @@ nsTString_CharT::RFindCharInSet( const CharT* aSet, PRInt32 aOffset ) const
   // to help performance.  this function also gets to keep the rickg style
   // indentation :-/
 PRInt32
-nsTString_CharT::ToInteger( PRInt32* aErrorCode, PRUint32 aRadix ) const
+nsTString_CharT::ToInteger( nsresult* aErrorCode, PRUint32 aRadix ) const
 {
   CharT*  cp=mData;
   PRInt32 theRadix=10; // base 10 unless base 16 detected, or overriden (aRadix != kAutoDetect)
diff --git a/xpcom/tests/TestCOMPtr.cpp b/xpcom/tests/TestCOMPtr.cpp
index 24f45cc60c3f..1e5d00d9419d 100644
--- a/xpcom/tests/TestCOMPtr.cpp
+++ b/xpcom/tests/TestCOMPtr.cpp
@@ -166,7 +166,7 @@ CreateIFoo( void** result )
     *result = foop;
 
     printf("<<CreateIFoo()\n");
-    return 0;
+    return NS_OK;
   }
 
 void
@@ -260,7 +260,7 @@ CreateIBar( void** result )
     *result = barp;
 
     printf("<<CreateIBar()\n");
-    return 0;
+    return NS_OK;
   }
 
 void
diff --git a/xpcom/tests/TestDeadlockDetector.cpp b/xpcom/tests/TestDeadlockDetector.cpp
index 2f9ba16ec77b..561bdc7b31ed 100644
--- a/xpcom/tests/TestDeadlockDetector.cpp
+++ b/xpcom/tests/TestDeadlockDetector.cpp
@@ -263,7 +263,7 @@ Sanity_Child()
     mozilla::Mutex m1("dd.sanity.m1");
     m1.Lock();
     m1.Lock();
-    return 0;                  // not reached
+    return NS_OK;                  // not reached
 }
 
 nsresult
@@ -293,7 +293,7 @@ Sanity2_Child()
     m1.Lock();
     m2.Lock();
     m1.Lock();
-    return 0;                  // not reached
+    return NS_OK;                  // not reached
 }
 
 nsresult
@@ -335,7 +335,7 @@ Sanity3_Child()
 
     m4.Lock();
     m1.Lock();
-    return 0;
+    return NS_OK;
 }
 
 nsresult
@@ -367,7 +367,7 @@ Sanity4_Child()
     m1.Enter();
     m2.Lock();
     m1.Enter();
-    return 0;
+    return NS_OK;
 }
 
 nsresult
@@ -427,7 +427,7 @@ TwoThreads_Child()
     PRThread* t2 = spawn(TwoThreads_thread, (void*) 1);
     PR_JoinThread(t2);
 
-    return 0;
+    return NS_OK;
 }
 
 nsresult
@@ -486,7 +486,7 @@ ContentionNoDeadlock_Child()
     for (PRUint32 i = 0; i < ArrayLength(cndMs); ++i)
         delete cndMs[i];
 
-    return 0;
+    return NS_OK;
 }
 
 nsresult
diff --git a/xpcom/tests/TestHashtables.cpp b/xpcom/tests/TestHashtables.cpp
index d1e0a57ffa10..0f74724f756e 100644
--- a/xpcom/tests/TestHashtables.cpp
+++ b/xpcom/tests/TestHashtables.cpp
@@ -324,7 +324,7 @@ CreateIFoo( IFoo** result )
     *result = foop;
 
     printf("<<CreateIFoo()\n");
-    return 0;
+    return NS_OK;
   }
 
 PLDHashOperator
diff --git a/xpcom/tests/TestRefPtr.cpp b/xpcom/tests/TestRefPtr.cpp
index 4707818210de..fd80cc9b8cd0 100644
--- a/xpcom/tests/TestRefPtr.cpp
+++ b/xpcom/tests/TestRefPtr.cpp
@@ -167,7 +167,7 @@ CreateFoo( void** result )
     *result = foop;
 
     printf("<<CreateFoo()\n");
-    return 0;
+    return NS_OK;
   }
 
 void
@@ -261,7 +261,7 @@ CreateBar( void** result )
     *result = barp;
 
     printf("<<CreateBar()\n");
-    return 0;
+    return NS_OK;
   }
 
 void
diff --git a/xpfe/appshell/src/nsXULWindow.cpp b/xpfe/appshell/src/nsXULWindow.cpp
index 1cbcc62198f1..7ab8a2ee86c4 100644
--- a/xpfe/appshell/src/nsXULWindow.cpp
+++ b/xpfe/appshell/src/nsXULWindow.cpp
@@ -1013,7 +1013,7 @@ bool nsXULWindow::LoadPositionFromXUL()
   PRInt32 currY = 0;
   PRInt32 currWidth = 0;
   PRInt32 currHeight = 0;
-  PRInt32 errorCode;
+  nsresult errorCode;
   PRInt32 temp;
 
   GetPositionAndSize(&currX, &currY, &currWidth, &currHeight);
@@ -1080,7 +1080,7 @@ bool nsXULWindow::LoadSizeFromXUL()
 
   PRInt32 currWidth = 0;
   PRInt32 currHeight = 0;
-  PRInt32 errorCode;
+  nsresult errorCode;
   PRInt32 temp;
 
   GetSize(&currWidth, &currHeight);
@@ -1212,7 +1212,7 @@ bool nsXULWindow::LoadMiscPersistentAttributesFromXUL()
   // zlevel
   rv = windowElement->GetAttribute(NS_LITERAL_STRING("zlevel"), stateString);
   if (NS_SUCCEEDED(rv) && stateString.Length() > 0) {
-    PRInt32  errorCode;
+    nsresult errorCode;
     PRUint32 zLevel = stateString.ToInteger(&errorCode);
     if (NS_SUCCEEDED(errorCode) && zLevel >= lowestZ && zLevel <= highestZ)
       SetZLevel(zLevel);