diff --git a/xpinstall/src/nsInstall.h b/xpinstall/src/nsInstall.h
index 11a3f690831..65b91d427da 100644
--- a/xpinstall/src/nsInstall.h
+++ b/xpinstall/src/nsInstall.h
@@ -332,7 +332,7 @@ class nsInstall
         void                SetChromeRegistry(CHROMEREG_IFACE* reg)
                                 { mChromeRegistry = reg; }
 
-        PRUint32   GetFinalStatus() { return mFinalStatus; }
+        PRInt32    GetFinalStatus() { return mFinalStatus; }
         PRBool     InInstallTransaction(void) { return mInstalledFiles != nsnull; }
 
         PRInt32    Alert(nsString& string);
@@ -361,7 +361,7 @@ class nsInstall
         nsInstallFolder*    mPackageFolder;
 
         PRBool              mUserCancelled;
-        PRUint32            mFinalStatus;
+        PRInt32             mFinalStatus;
 
         PRBool              mUninstallPackage;
         PRBool              mRegisterPackage;
diff --git a/xpinstall/src/nsInstallFile.cpp b/xpinstall/src/nsInstallFile.cpp
index 6766ed16a91..530df2eb1ab 100644
--- a/xpinstall/src/nsInstallFile.cpp
+++ b/xpinstall/src/nsInstallFile.cpp
@@ -153,7 +153,7 @@ nsInstallFile::nsInstallFile(nsInstall* inInstall,
         }
         else
         {
-            nsresult rv = inPartialPath.Mid(subString, offset, nodeLength);
+            inPartialPath.Mid(subString, offset, nodeLength);
             mFinalFile->Append(subString);
             offset += nodeLength + 1;
             if (!finished)
diff --git a/xpinstall/src/nsInstallFolder.cpp b/xpinstall/src/nsInstallFolder.cpp
index f37538683a7..e862c6bf770 100644
--- a/xpinstall/src/nsInstallFolder.cpp
+++ b/xpinstall/src/nsInstallFolder.cpp
@@ -650,7 +650,7 @@ nsInstallFolder::AppendXPPath(const nsString& aRelativePath)
             mFileSpec = nsnull;
             break;
         }
-        else if ( curr == kNotFound )
+        else if ( curr == PRUint32(kNotFound) )
         {
             // last segment
             aRelativePath.Right(segment,aRelativePath.Length() - start);
diff --git a/xpinstall/src/nsInstallTrigger.cpp b/xpinstall/src/nsInstallTrigger.cpp
index 76cb78fa02b..6b4f09fd6fb 100644
--- a/xpinstall/src/nsInstallTrigger.cpp
+++ b/xpinstall/src/nsInstallTrigger.cpp
@@ -181,13 +181,10 @@ nsInstallTrigger::HandleContent(const char * aContentType,
 
 
     // Get the global object of the target window for StartSoftwareUpdate
-    nsIScriptGlobalObject* globalObject;
     nsCOMPtr<nsIScriptGlobalObjectOwner> globalObjectOwner = 
                                          do_QueryInterface(aWindowContext);
-    if ( globalObjectOwner )
-    {
-        globalObject = globalObjectOwner->GetScriptGlobalObject();
-    }
+    nsIScriptGlobalObject* globalObject =
+      globalObjectOwner ? globalObjectOwner->GetScriptGlobalObject() : nsnull;
     if ( !globalObject )
         return NS_ERROR_INVALID_ARG;
 
diff --git a/xpinstall/src/nsXPITriggerInfo.cpp b/xpinstall/src/nsXPITriggerInfo.cpp
index 3743d8b8ab5..70076d2d338 100644
--- a/xpinstall/src/nsXPITriggerInfo.cpp
+++ b/xpinstall/src/nsXPITriggerInfo.cpp
@@ -59,7 +59,7 @@ nsXPITriggerItem::nsXPITriggerItem( const PRUnichar* aName,
                                     const PRUnichar* aIconURL,
                                     const char* aHash,
                                     PRInt32 aFlags)
-    : mName(aName), mURL(aURL), mIconURL(aIconURL), mFlags(aFlags), mHashFound(PR_FALSE)
+    : mName(aName), mURL(aURL), mIconURL(aIconURL), mHashFound(PR_FALSE), mFlags(aFlags)
 {
     MOZ_COUNT_CTOR(nsXPITriggerItem);
 
@@ -97,7 +97,6 @@ nsXPITriggerItem::nsXPITriggerItem( const PRUnichar* aName,
     {
         mHashFound = PR_TRUE;
 
-        PRUint32 htype = 1;
         char * colon = PL_strchr(aHash, ':');
         if (colon)
         {