diff --git a/include/X11/extensions/securproto.h b/include/X11/extensions/securproto.h
index d9e120c..7c68313 100644
--- a/include/X11/extensions/securproto.h
+++ b/include/X11/extensions/securproto.h
@@ -27,6 +27,7 @@ from The Open Group.
 #ifndef _SECURPROTO_H
 #define _SECURPROTO_H
 
+#include <X11/Xmd.h>
 #include <X11/extensions/secur.h>
 
 #define X_SecurityQueryVersion		0