@ -189,6 +189,9 @@ static struct subbackend_state *multi_backend_get_subbackend(struct wlr_multi_ba
bool wlr_multi_backend_add(struct wlr_backend *_multi,
struct wlr_backend *backend) {
assert(_multi && backend);
assert(_multi != backend);
struct wlr_multi_backend *multi = multi_backend_from_backend(_multi);
if (multi_backend_get_subbackend(multi, backend)) {