diff --git a/sway/lock.c b/sway/lock.c
index ae44aa40b..534561720 100644
--- a/sway/lock.c
+++ b/sway/lock.c
@@ -104,7 +104,7 @@ static void handle_new_surface(struct wl_listener *listener, void *data) {
 	surf->surface = lock_surface->surface;
 	surf->output = output;
 	surf->map.notify = handle_surface_map;
-	wl_signal_add(&lock_surface->events.map, &surf->map);
+	wl_signal_add(&lock_surface->surface->events.map, &surf->map);
 	surf->destroy.notify = handle_surface_destroy;
 	wl_signal_add(&lock_surface->events.destroy, &surf->destroy);
 	surf->surface_commit.notify = handle_surface_commit;