diff --git a/qom/object.c b/qom/object.c
index 00bb3b0..444e2fc 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -481,6 +481,8 @@ Object *object_dynamic_cast_assert(Object *obj, const char *typename)
 {
     Object *inst;
 
+    g_assert(obj != NULL);
+
     inst = object_dynamic_cast(obj, typename);
 
     if (!inst) {