diff --git a/src/widgets/valnum.h b/src/widgets/valnum.h
index bd0bbf35f..e2aa987fd 100644
--- a/src/widgets/valnum.h
+++ b/src/widgets/valnum.h
@@ -11,6 +11,7 @@
 #ifndef _WIDGETS_VALNUM_H_
 #define _WIDGETS_VALNUM_H_
 
+#include "../MemoryX.h"
 #include <wx/defs.h>
 
 #if wxUSE_VALIDATORS