diff --git a/content/base/src/nsContentUtils.cpp b/content/base/src/nsContentUtils.cpp
index 43e35cc07ea..ccc4f1433d5 100644
--- a/content/base/src/nsContentUtils.cpp
+++ b/content/base/src/nsContentUtils.cpp
@@ -1195,7 +1195,8 @@ nsContentUtils::CanCallerAccess(nsIDOMNode *aNode)
   // with the system principal games?  But really, there should be a simpler
   // API here, dammit.
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
-  sSecurityManager->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  nsresult rv = sSecurityManager->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  NS_ENSURE_SUCCESS(rv, PR_FALSE);
 
   if (!subjectPrincipal) {
     // we're running as system, grant access to the node.
@@ -1217,7 +1218,8 @@ nsContentUtils::CanCallerAccess(nsPIDOMWindow* aWindow)
   // with the system principal games?  But really, there should be a simpler
   // API here, dammit.
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
-  sSecurityManager->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  nsresult rv = sSecurityManager->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  NS_ENSURE_SUCCESS(rv, PR_FALSE);
 
   if (!subjectPrincipal) {
     // we're running as system, grant access to the node.
diff --git a/content/base/src/nsDOMFileReader.cpp b/content/base/src/nsDOMFileReader.cpp
index ae3f34b3e6c..eabbe84aff1 100644
--- a/content/base/src/nsDOMFileReader.cpp
+++ b/content/base/src/nsDOMFileReader.cpp
@@ -179,7 +179,8 @@ nsDOMFileReader::Init()
   nsIScriptSecurityManager *secMan = nsContentUtils::GetSecurityManager();
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
   if (secMan) {
-    secMan->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+    nsresult rv = secMan->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+    NS_ENSURE_SUCCESS(rv, rv);
   }
   NS_ENSURE_STATE(subjectPrincipal);
   mPrincipal = subjectPrincipal;
diff --git a/content/base/src/nsDOMParser.cpp b/content/base/src/nsDOMParser.cpp
index 041a8e10bf9..a1fcb3a4faa 100644
--- a/content/base/src/nsDOMParser.cpp
+++ b/content/base/src/nsDOMParser.cpp
@@ -406,7 +406,8 @@ nsDOMParser::Initialize(nsISupports* aOwner, JSContext* cx, JSObject* obj,
     nsIScriptSecurityManager* secMan = nsContentUtils::GetSecurityManager();
     NS_ENSURE_TRUE(secMan, NS_ERROR_UNEXPECTED);
 
-    secMan->GetSubjectPrincipal(getter_AddRefs(prin));
+    nsresult rv = secMan->GetSubjectPrincipal(getter_AddRefs(prin));
+    NS_ENSURE_SUCCESS(rv, rv);
 
     // We're called from JS; there better be a subject principal, really.
     NS_ENSURE_TRUE(prin, NS_ERROR_UNEXPECTED);
@@ -463,7 +464,8 @@ nsDOMParser::Init(nsIPrincipal *aPrincipal, nsIURI *aDocumentURI,
     nsIScriptSecurityManager* secMan = nsContentUtils::GetSecurityManager();
     NS_ENSURE_TRUE(secMan, NS_ERROR_UNEXPECTED);
 
-    secMan->GetSubjectPrincipal(getter_AddRefs(principal));
+    nsresult rv = secMan->GetSubjectPrincipal(getter_AddRefs(principal));
+    NS_ENSURE_SUCCESS(rv, rv);
 
     // We're called from JS; there better be a subject principal, really.
     NS_ENSURE_TRUE(principal, NS_ERROR_UNEXPECTED);
diff --git a/content/base/src/nsXMLHttpRequest.cpp b/content/base/src/nsXMLHttpRequest.cpp
index d7799d26759..fa41e1cd65b 100644
--- a/content/base/src/nsXMLHttpRequest.cpp
+++ b/content/base/src/nsXMLHttpRequest.cpp
@@ -480,7 +480,8 @@ nsXMLHttpRequest::Init()
   nsIScriptSecurityManager *secMan = nsContentUtils::GetSecurityManager();
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
   if (secMan) {
-    secMan->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+    nsresult rv = secMan->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+    NS_ENSURE_SUCCESS(rv, rv);
   }
   NS_ENSURE_STATE(subjectPrincipal);
   mPrincipal = subjectPrincipal;
diff --git a/content/events/src/nsDOMDataTransfer.cpp b/content/events/src/nsDOMDataTransfer.cpp
index 4b9259ae131..0ba97ef0875 100644
--- a/content/events/src/nsDOMDataTransfer.cpp
+++ b/content/events/src/nsDOMDataTransfer.cpp
@@ -803,7 +803,9 @@ nsDOMDataTransfer::GetCurrentPrincipal()
   nsIScriptSecurityManager* ssm = nsContentUtils::GetSecurityManager();
 
   nsCOMPtr<nsIPrincipal> currentPrincipal;
-  ssm->GetSubjectPrincipal(getter_AddRefs(currentPrincipal));
+  nsresult rv = ssm->GetSubjectPrincipal(getter_AddRefs(currentPrincipal));
+  NS_ENSURE_SUCCESS(rv, nsnull);
+
   if (!currentPrincipal)
     ssm->GetSystemPrincipal(getter_AddRefs(currentPrincipal));
 
diff --git a/content/xslt/src/xslt/txMozillaXSLTProcessor.cpp b/content/xslt/src/xslt/txMozillaXSLTProcessor.cpp
index 210ea3c51ae..b558f47a2e1 100644
--- a/content/xslt/src/xslt/txMozillaXSLTProcessor.cpp
+++ b/content/xslt/src/xslt/txMozillaXSLTProcessor.cpp
@@ -1265,7 +1265,8 @@ txMozillaXSLTProcessor::Initialize(nsISupports* aOwner, JSContext* cx,
     nsIScriptSecurityManager* secMan = nsContentUtils::GetSecurityManager();
     NS_ENSURE_TRUE(secMan, NS_ERROR_UNEXPECTED);
 
-    secMan->GetSubjectPrincipal(getter_AddRefs(prin));
+    nsresult rv = secMan->GetSubjectPrincipal(getter_AddRefs(prin));
+    NS_ENSURE_SUCCESS(rv, rv);
     NS_ENSURE_TRUE(prin, NS_ERROR_UNEXPECTED);
 
     return Init(prin);
diff --git a/dom/src/storage/nsDOMStorage.cpp b/dom/src/storage/nsDOMStorage.cpp
index 78b985ab927..1c85f4766a3 100644
--- a/dom/src/storage/nsDOMStorage.cpp
+++ b/dom/src/storage/nsDOMStorage.cpp
@@ -137,8 +137,9 @@ static PRBool
 IsCallerSecure()
 {
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
-  nsContentUtils::GetSecurityManager()->
-    GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  nsresult rv = nsContentUtils::GetSecurityManager()->
+                  GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  NS_ENSURE_SUCCESS(rv, PR_FALSE);
 
   if (!subjectPrincipal) {
     // No subject principal means no code is running. Default to not
@@ -161,7 +162,7 @@ IsCallerSecure()
   }
 
   PRBool isHttps = PR_FALSE;
-  nsresult rv = innerUri->SchemeIs("https", &isHttps);
+  rv = innerUri->SchemeIs("https", &isHttps);
 
   return NS_SUCCEEDED(rv) && isHttps;
 }
@@ -1470,8 +1471,9 @@ nsDOMStorage::CanUseStorage(PRPackedBool* aSessionOnly)
     return PR_TRUE;
 
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
-  nsContentUtils::GetSecurityManager()->
-    GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  nsresult rv = nsContentUtils::GetSecurityManager()->
+                  GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  NS_ENSURE_SUCCESS(rv, PR_FALSE);
 
   // if subjectPrincipal were null we'd have returned after
   // IsCallerChrome().
@@ -1533,7 +1535,8 @@ nsDOMStorage::CacheStoragePermissions()
     return PR_FALSE;
 
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
-  ssm->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  nsresult rv = ssm->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  NS_ENSURE_SUCCESS(rv, PR_FALSE);
 
   NS_ASSERTION(mSecurityChecker, "Has non-null mSecurityChecker");
   return mSecurityChecker->CanAccess(subjectPrincipal);
diff --git a/layout/style/nsCSSStyleSheet.cpp b/layout/style/nsCSSStyleSheet.cpp
index c7091bd0c3f..54e35d9c6ca 100644
--- a/layout/style/nsCSSStyleSheet.cpp
+++ b/layout/style/nsCSSStyleSheet.cpp
@@ -1576,14 +1576,15 @@ nsCSSStyleSheet::SubjectSubsumesInnerPrincipal() const
     nsContentUtils::GetSecurityManager();
 
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
-  securityManager->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  nsresult rv = securityManager->GetSubjectPrincipal(getter_AddRefs(subjectPrincipal));
+  NS_ENSURE_SUCCESS(rv, rv);
 
   if (!subjectPrincipal) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
   PRBool subsumes;
-  nsresult rv = subjectPrincipal->Subsumes(mInner->mPrincipal, &subsumes);
+  rv = subjectPrincipal->Subsumes(mInner->mPrincipal, &subsumes);
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (subsumes) {
diff --git a/security/manager/ssl/src/nsCrypto.cpp b/security/manager/ssl/src/nsCrypto.cpp
index 9fe741fb868..d0781ddeeba 100644
--- a/security/manager/ssl/src/nsCrypto.cpp
+++ b/security/manager/ssl/src/nsCrypto.cpp
@@ -2013,7 +2013,8 @@ nsCrypto::GenerateCRMFRequest(nsIDOMCRMFObject** aReturn)
   NS_ENSURE_TRUE(secMan, NS_ERROR_UNEXPECTED);
   
   nsCOMPtr<nsIPrincipal> principals;
-  secMan->GetSubjectPrincipal(getter_AddRefs(principals));
+  nsresult rv = secMan->GetSubjectPrincipal(getter_AddRefs(principals));
+  NS_ENSURE_SUCCESS(rv, rv);
   NS_ENSURE_TRUE(principals, NS_ERROR_UNEXPECTED);
   
   nsCryptoRunArgs *args = new nsCryptoRunArgs();
@@ -2031,7 +2032,7 @@ nsCrypto::GenerateCRMFRequest(nsIDOMCRMFObject** aReturn)
   if (!cryptoRunnable)
     return NS_ERROR_OUT_OF_MEMORY;
 
-  nsresult rv = NS_DispatchToMainThread(cryptoRunnable);
+  rv = NS_DispatchToMainThread(cryptoRunnable);
   if (NS_FAILED(rv))
     delete cryptoRunnable;
 
diff --git a/xpinstall/src/nsJSInstallTriggerGlobal.cpp b/xpinstall/src/nsJSInstallTriggerGlobal.cpp
index 80f1e3afc64..6fe45342e17 100644
--- a/xpinstall/src/nsJSInstallTriggerGlobal.cpp
+++ b/xpinstall/src/nsJSInstallTriggerGlobal.cpp
@@ -256,8 +256,9 @@ InstallTriggerGlobalInstall(JSContext *cx, JSObject *obj, uintN argc, jsval *arg
   }
   // get the principal.  if it doesn't exist, die.
   nsCOMPtr<nsIPrincipal> principal;
-  secman->GetSubjectPrincipal(getter_AddRefs(principal));
-  if (!principal)
+  nsresult rv = secman->GetSubjectPrincipal(getter_AddRefs(principal));
+
+  if (NS_FAILED(rv) || !principal)
   {
     JS_ReportError(cx, "Could not get the Subject Principal during InstallTrigger.Install()");
     return JS_FALSE;
@@ -369,7 +370,7 @@ InstallTriggerGlobalInstall(JSContext *cx, JSObject *obj, uintN argc, jsval *arg
             }
 
             // Make sure we're allowed to load this URL and the icon URL
-            nsresult rv = InstallTriggerCheckLoadURIFromScript(cx, xpiURL);
+            rv = InstallTriggerCheckLoadURIFromScript(cx, xpiURL);
             if (NS_FAILED(rv))
                 abortLoad = PR_TRUE;
 
@@ -404,8 +405,8 @@ InstallTriggerGlobalInstall(JSContext *cx, JSObject *obj, uintN argc, jsval *arg
     if (!abortLoad && trigger->Size() > 0)
     {
         nsCOMPtr<nsIURI> checkuri;
-        nsresult rv = nativeThis->GetOriginatingURI(globalObject,
-                                                    getter_AddRefs(checkuri));
+        rv = nativeThis->GetOriginatingURI(globalObject,
+                                           getter_AddRefs(checkuri));
         if (NS_SUCCEEDED(rv))
         {
             nsCOMPtr<nsIDOMWindowInternal> win(do_QueryInterface(globalObject));
diff --git a/xpinstall/src/nsXPITriggerInfo.cpp b/xpinstall/src/nsXPITriggerInfo.cpp
index 81710460601..2f53df92018 100644
--- a/xpinstall/src/nsXPITriggerInfo.cpp
+++ b/xpinstall/src/nsXPITriggerInfo.cpp
@@ -284,8 +284,9 @@ XPITriggerEvent::Run()
     }
 
     nsCOMPtr<nsIPrincipal> principal;
-    secman->GetSubjectPrincipal(getter_AddRefs(principal));
-    if (!principal)
+    nsresult rv = secman->GetSubjectPrincipal(getter_AddRefs(principal));
+
+    if (NS_FAILED(rv) || !principal)
     {
          JS_ReportError(cx, "Could not get principal from script security manager");
          return 0;