diff --git a/src/frontends/qt4/Menus.h b/src/frontends/qt4/Menus.h
index 9ba0c10d58..d0bc687591 100644
--- a/src/frontends/qt4/Menus.h
+++ b/src/frontends/qt4/Menus.h
@@ -20,6 +20,7 @@
 #include <vector>
 
 class QString;
+class QMenuBar;
 
 namespace lyx {