diff --git a/gtk/gtksocket.c b/gtk/gtksocket.c
index a9b5b7457d..b78991de7b 100644
--- a/gtk/gtksocket.c
+++ b/gtk/gtksocket.c
@@ -42,6 +42,7 @@
 #include "gtkdnd.h"
 #include "gtkdebug.h"
 #include "gtkintl.h"
+#include "gtkwidgetprivate.h"
 
 
 /**