diff --git a/gdk/gdkcontentserializer.c b/gdk/gdkcontentserializer.c
index 92cbb2df6b..7b99690224 100644
--- a/gdk/gdkcontentserializer.c
+++ b/gdk/gdkcontentserializer.c
@@ -895,8 +895,8 @@ init (void)
       gdk_content_register_serializer (G_TYPE_STRING,
                                        mime,
                                        string_serializer,
-                                       mime,
-                                       g_free);
+                                       (gpointer) charset,
+                                       NULL);
     }
   gdk_content_register_serializer (G_TYPE_STRING,
                                    "text/plain",