diff --git a/extra/ui/x11/x11.factor b/extra/ui/x11/x11.factor
index 6a0560cb28..e4794452c7 100755
--- a/extra/ui/x11/x11.factor
+++ b/extra/ui/x11/x11.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2005, 2007 Eduardo Cavazos and Slava Pestov
 ! See http://factorcode.org/license.txt for BSD license.
-USING: alien arrays ui ui.gadgets ui.gestures ui.backend
+USING: alien alien.c-types arrays ui ui.gadgets ui.gestures ui.backend
 ui.clipboards ui.gadgets.worlds assocs kernel math namespaces
 opengl sequences strings x11.xlib x11.events x11.xim x11.glx
 x11.clipboard x11.constants x11.windows io.utf8 combinators