diff --git a/mozilla/xpfe/bootstrap/appleevents/nsWindowUtils.cpp b/mozilla/xpfe/bootstrap/appleevents/nsWindowUtils.cpp
index 09e2620bda7..b4b8f6c1340 100644
--- a/mozilla/xpfe/bootstrap/appleevents/nsWindowUtils.cpp
+++ b/mozilla/xpfe/bootstrap/appleevents/nsWindowUtils.cpp
@@ -60,6 +60,7 @@
 #include "nsWindowUtils.h"
 #include "nsMacUtils.h"
 #include "nsXPIDLString.h"
+#include "nsIDocShellTreeItem.h"
 #include "nsWindowUtils.h"
 #include "nsReadableUtils.h"