diff --git a/mozilla/toolkit/xre/nsXREDirProvider.cpp b/mozilla/toolkit/xre/nsXREDirProvider.cpp
index 9f126f1be8f..2098eade707 100644
--- a/mozilla/toolkit/xre/nsXREDirProvider.cpp
+++ b/mozilla/toolkit/xre/nsXREDirProvider.cpp
@@ -63,6 +63,10 @@
 #ifdef XP_WIN
 #include <windows.h>
 #include <shlobj.h>
+// This is not defined by VC6. 
+#ifndef CSIDL_LOCAL_APPDATA
+#define CSIDL_LOCAL_APPDATA             0x001C
+#endif
 #endif
 #ifdef XP_MACOSX
 #include "nsILocalFileMac.h"