diff --git a/capplet/settings/mail-capplet-shell.c b/capplet/settings/mail-capplet-shell.c
index 7a9a4fa412..c14af1b609 100644
--- a/capplet/settings/mail-capplet-shell.c
+++ b/capplet/settings/mail-capplet-shell.c
@@ -26,6 +26,8 @@
 #ifdef HAVE_CONFIG_H
 #  include <config.h>
 #endif
+
+#include <gtk/gtkx.h>
 #include <glib/gi18n.h>
 #include <glib/gstdio.h>
 #include <gconf/gconf-client.h>