diff --git a/mjit.c b/mjit.c
index db2811e94f..a5c75e5103 100644
--- a/mjit.c
+++ b/mjit.c
@@ -1379,6 +1379,7 @@ mjit_init(struct mjit_options *opts)
     valid_class_serials = rb_hash_new();
     rb_obj_hide(valid_class_serials);
     rb_gc_register_mark_object(valid_class_serials);
+    mjit_add_class_serial(RCLASS_SERIAL(rb_cObject));
     if (RCLASS_CONST_TBL(rb_cObject)) {
         rb_id_table_foreach(RCLASS_CONST_TBL(rb_cObject), valid_class_serials_add_i, NULL);
     }