diff --git a/cfg/gtk.cfg b/cfg/gtk.cfg
index b3a3c40b6..0859db1a6 100644
--- a/cfg/gtk.cfg
+++ b/cfg/gtk.cfg
@@ -9,6 +9,9 @@
   <define name="G_CALLBACK(cb)" value="cb"/>
   <define name="G_LIKELY(expr)" value="(expr)"/>
   <define name="G_UNLIKELY(expr)" value="(expr)"/>
+  <define name="_G_TYPE_CIC(ip, gt, ct)" value="((ct*) ip)"/>
+  <define name="_G_TYPE_CCC(cp, gt, ct)" value="((ct*) cp)"/>
+  <define name="G_TYPE_CHECK_INSTANCE_CAST(instance, g_type, c_type)" value="(_G_TYPE_CIC ((instance), (g_type), c_type))"/>
   <define name="G_OBJECT(obj)" value="(GObject*)(obj)"/>
   <define name="GTK_BOX(obj)" value="((GtkBox*)(obj))"/>
   <define name="GTK_CONTAINER(obj)" value="((GtkContainer*)(obj))"/>