diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
index 28b993b7b..bc4376fb5 100644
--- a/src/libsystemd/sd-bus/sd-bus.c
+++ b/src/libsystemd/sd-bus/sd-bus.c
@@ -142,6 +142,7 @@ static void bus_free(sd_bus *b) {
         hashmap_free_free(b->reply_callbacks);
         prioq_free(b->reply_callbacks_prioq);
 
+        assert(b->match_callbacks.type == BUS_MATCH_ROOT);
         bus_match_free(&b->match_callbacks);
 
         hashmap_free_free(b->vtable_methods);