diff --git a/mozilla/xpcom/ds/nsWindowsRegKey.cpp b/mozilla/xpcom/ds/nsWindowsRegKey.cpp
index 18428345d20..57519359596 100644
--- a/mozilla/xpcom/ds/nsWindowsRegKey.cpp
+++ b/mozilla/xpcom/ds/nsWindowsRegKey.cpp
@@ -38,6 +38,7 @@
 
 #include <windows.h>
 #include <shlwapi.h>
+#include <stdlib.h>
 #include "nsWindowsRegKey.h"
 #include "nsNativeCharsetUtils.h"
 #include "nsString.h"