diff --git a/mozilla/content/html/style/src/nsCSSLoader.cpp b/mozilla/content/html/style/src/nsCSSLoader.cpp
index 2cecf1ca6c8..690a160181b 100644
--- a/mozilla/content/html/style/src/nsCSSLoader.cpp
+++ b/mozilla/content/html/style/src/nsCSSLoader.cpp
@@ -461,7 +461,7 @@ CSSLoaderImpl::CSSLoaderImpl(void)
   mCaseSensitive = PR_FALSE;
   mNavQuirkMode = PR_FALSE;
   mParsers = nsnull;
-  SetCharset(nsString(""));
+  SetCharset(nsAutoString());
 }
 
 static PRBool ReleaseSheet(nsHashKey* aKey, void* aData, void* aClosure)
diff --git a/mozilla/layout/html/style/src/nsCSSLoader.cpp b/mozilla/layout/html/style/src/nsCSSLoader.cpp
index 2cecf1ca6c8..690a160181b 100644
--- a/mozilla/layout/html/style/src/nsCSSLoader.cpp
+++ b/mozilla/layout/html/style/src/nsCSSLoader.cpp
@@ -461,7 +461,7 @@ CSSLoaderImpl::CSSLoaderImpl(void)
   mCaseSensitive = PR_FALSE;
   mNavQuirkMode = PR_FALSE;
   mParsers = nsnull;
-  SetCharset(nsString(""));
+  SetCharset(nsAutoString());
 }
 
 static PRBool ReleaseSheet(nsHashKey* aKey, void* aData, void* aClosure)
diff --git a/mozilla/layout/style/nsCSSLoader.cpp b/mozilla/layout/style/nsCSSLoader.cpp
index 2cecf1ca6c8..690a160181b 100644
--- a/mozilla/layout/style/nsCSSLoader.cpp
+++ b/mozilla/layout/style/nsCSSLoader.cpp
@@ -461,7 +461,7 @@ CSSLoaderImpl::CSSLoaderImpl(void)
   mCaseSensitive = PR_FALSE;
   mNavQuirkMode = PR_FALSE;
   mParsers = nsnull;
-  SetCharset(nsString(""));
+  SetCharset(nsAutoString());
 }
 
 static PRBool ReleaseSheet(nsHashKey* aKey, void* aData, void* aClosure)