diff --git a/include/osgViewer/ViewerEventHandlers b/include/osgViewer/ViewerEventHandlers
index e59e2156e..0bbcc2564 100644
--- a/include/osgViewer/ViewerEventHandlers
+++ b/include/osgViewer/ViewerEventHandlers
@@ -15,6 +15,7 @@
 #define OSGVIEWER_VIEWEREVENTHANDLER 1
 
 #include <osgGA/GUIEventHandler>
+#include <osgViewer/GraphicsWindow>
 
 namespace osgViewer {