diff --git a/src/msw/mdi.cpp b/src/msw/mdi.cpp
index ee869d9759..1d295a13dc 100644
--- a/src/msw/mdi.cpp
+++ b/src/msw/mdi.cpp
@@ -245,7 +245,7 @@ wxMDIParentFrame::~wxMDIParentFrame()
     if ( m_hMenu )
     {
         ::DestroyMenu((HMENU)m_hMenu);
-        m_hMenu = NULL;
+        m_hMenu = (WXHMENU)NULL;
     }
 
     if ( m_clientWindow )