diff --git a/src/msw/window.cpp b/src/msw/window.cpp
index d72864aa13..6e4f99c390 100644
--- a/src/msw/window.cpp
+++ b/src/msw/window.cpp
@@ -47,6 +47,7 @@
     #include "wx/msgdlg.h"
     #include "wx/settings.h"
     #include "wx/statbox.h"
+    #include "wx/sizer.h"
 #endif
 
 #if wxUSE_OWNER_DRAWN && !defined(__WXUNIVERSAL__)