diff --git a/sub/osd_dummy.c b/sub/osd_dummy.c
index 061f6446c3..5c3cc76200 100644
--- a/sub/osd_dummy.c
+++ b/sub/osd_dummy.c
@@ -27,7 +27,7 @@ void osd_object_get_bitmaps(struct osd_state *osd, struct osd_object *obj,
     *out_imgs = (struct sub_bitmaps) {0};
 }
 
-void osd_set_external(struct osd_state *osd, char *id, int res_x, int res_y,
+void osd_set_external(struct osd_state *osd, void *id, int res_x, int res_y,
                       char *text)
 {
 }