diff --git a/libweston/compositor.c b/libweston/compositor.c
index 91425fb1..fe92a462 100644
--- a/libweston/compositor.c
+++ b/libweston/compositor.c
@@ -2303,6 +2303,10 @@ weston_surface_unref(struct weston_surface *surface)
 	struct weston_pointer_constraint *constraint, *next_constraint;
 	struct weston_paint_node *pnode, *pntmp;
 
+	if (!surface)
+		return;
+
+	assert(surface->ref_count > 0);
 	if (--surface->ref_count > 0)
 		return;