diff --git a/widget/xpwidgets/nsBaseWidget.cpp b/widget/xpwidgets/nsBaseWidget.cpp
index 0de9a74fcff..5044f3f1577 100644
--- a/widget/xpwidgets/nsBaseWidget.cpp
+++ b/widget/xpwidgets/nsBaseWidget.cpp
@@ -19,6 +19,7 @@
 #include "nsISimpleEnumerator.h"
 #include "nsIContent.h"
 #include "nsIDocument.h"
+#include "nsIPresShell.h"
 #include "nsIServiceManager.h"
 #include "mozilla/Preferences.h"
 #include "BasicLayers.h"