1 files changed, 1 insertions, 0 deletions
diff --git a/src/object.c b/src/object.c
index f8f41bfe8..c834ee04f 100644
--- a/src/object.c
+++ b/src/object.c
@@ -487,6 +487,7 @@ mrb_obj_is_kind_of(mrb_state *mrb, mrb_value obj, struct RClass *c)
       mrb_raise(mrb, E_TYPE_ERROR, "class or module required");
   }
 
+  c = c->origin;
   while (cl) {
     if (cl == c || cl->mt == c->mt)
       return TRUE;