--- a/modules/libpref/src/nsPrefService.cpp
+++ b/modules/libpref/src/nsPrefService.cpp
@@ -599,17 +599,17 @@ static nsresult openPrefFile(nsIFile* aF
     return rv;        
 
   PRInt64 fileSize;
   rv = aFile->GetFileSize(&fileSize);
   if (NS_FAILED(rv))
     return rv;
 
   char *fileBuffer = nsnull;
-  fileBuffer = new char[nsInt64(fileSize)];
+  fileBuffer = new char[fileSize];
   if (fileBuffer == nsnull)
     return NS_ERROR_OUT_OF_MEMORY;
 
   PRUint32 amtRead = 0;
   rv = inStr->Read(fileBuffer, fileSize, &amtRead);
   if (NS_FAILED(rv)) {
     delete fileBuffer;
     return rv;