diff --git a/src/tray/na-tray-child.h b/src/tray/na-tray-child.h
index 5e4aba853..52b5545f7 100644
--- a/src/tray/na-tray-child.h
+++ b/src/tray/na-tray-child.h
@@ -24,6 +24,7 @@
 #define __NA_TRAY_CHILD_H__
 
 #include <gtk/gtk.h>
+#include <gtk/gtkx.h>
 #include <gdk/gdkx.h>
 
 G_BEGIN_DECLS