diff --git a/ChangeLog b/ChangeLog
index b8a2526872..76013df34f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Dec  3 23:06:20 2013  Narihiro Nakamura  <authornari@gmail.com>
+
+	* object.c (rb_obj_clone): don't copy FL_WB_PROTECTED of a
+	  original object.
+
 Tue Dec  3 22:32:18 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* hash.c (rb_hash_recursive): make similar (recursive) constructs
diff --git a/object.c b/object.c
index f316a1bcbe..87e9608e76 100644
--- a/object.c
+++ b/object.c
@@ -336,7 +336,7 @@ rb_obj_clone(VALUE obj)
     }
     clone = rb_obj_alloc(rb_obj_class(obj));
     RBASIC(clone)->flags &= (FL_TAINT|FL_PROMOTED|FL_WB_PROTECTED);
-    RBASIC(clone)->flags |= RBASIC(obj)->flags & ~(FL_PROMOTED|FL_FREEZE|FL_FINALIZE);
+    RBASIC(clone)->flags |= RBASIC(obj)->flags & ~(FL_PROMOTED|FL_FREEZE|FL_FINALIZE|FL_WB_PROTECTED);
 
     singleton = rb_singleton_class_clone_and_attach(obj, clone);
     RBASIC_SET_CLASS(clone, singleton);