diff --git a/mozilla/widget/src/gtk/nsKeyboardUtils.cpp b/mozilla/widget/src/gtk/nsKeyboardUtils.cpp
index 572886a6a43..88017d9cf70 100644
--- a/mozilla/widget/src/gtk/nsKeyboardUtils.cpp
+++ b/mozilla/widget/src/gtk/nsKeyboardUtils.cpp
@@ -22,6 +22,7 @@
 #endif
 #include <X11/keysym.h>
 #include <gdk/gdkx.h>
+#include <string.h>
 #include "nsKeyboardUtils.h"
 #include "nspr.h"