diff --git a/ChangeLog b/ChangeLog
index 11ae3517ea..edad3d04ef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Aug  3 17:15:06 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* object.c (rb_obj_clone2): restrict freeze option to true other
+	  than false which only has the effect.  [Feature #12300]
+
 Wed Aug  3 10:47:07 2016  Koichi Sasada  <ko1@atdot.net>
 
 	* vm_core.h: introduce VM_FRAME_RUBYFRAME_P()
diff --git a/object.c b/object.c
index a4a87db4d6..c58a46b293 100644
--- a/object.c
+++ b/object.c
@@ -339,6 +339,10 @@ rb_obj_clone2(int argc, VALUE *argv, VALUE obj)
     if (!NIL_P(opt)) {
 	rb_get_kwargs(opt, keyword_ids, 0, 1, kwargs);
 	kwfreeze = kwargs[0];
+	if (kwfreeze != Qundef && kwfreeze != Qtrue && kwfreeze != Qfalse) {
+	    rb_raise(rb_eArgError, "unexpected value for freeze: %s",
+		     rb_builtin_class_name(kwfreeze));
+	}
     }
 
     if (rb_special_const_p(obj)) {