diff --git a/glib/ghook.h b/glib/ghook.h
index c738a0c02..62b57f3d9 100644
--- a/glib/ghook.h
+++ b/glib/ghook.h
@@ -56,6 +56,8 @@ typedef enum
 {
   G_HOOK_FLAG_ACTIVE	    = 1 << 0,
   G_HOOK_FLAG_IN_CALL	    = 1 << 1,
+  G_HOOK_FLAG_RESERVED1     = 1 << 2, /*< private >*/
+  G_HOOK_FLAG_RESERVED2     = 1 << 3, /*< private >*/
   G_HOOK_FLAG_MASK	    = 0x0f
 } G_GNUC_FLAG_ENUM GHookFlagMask;
 #define G_HOOK_FLAG_USER_SHIFT	(4)