diff --git a/ChangeLog b/ChangeLog
index 06407259d5..769c0f12ba 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu Oct 13 00:39:08 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* test/ruby/test_array.rb (test_sort_bang_with_freeze): make a
+	  clone to copy a <=> singleton method, instead of dup.  which
+	  element will be called is not predictable.
+	  [ruby-core:76088] [Bug #12509]
+
 Thu Oct 13 00:21:27 2016  Simon Soriano  <simon0191@gmail.com>
 
 	* doc/extension.rdoc: Replace "You can defined hooked variables"
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index a19e22aab4..bdb603bec5 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1488,7 +1488,7 @@ class TestArray < Test::Unit::TestCase
         1
       }
     }
-    o2 = o1.dup
+    o2 = o1.clone
     ary << o1 << o2
     orig = ary.dup
     assert_raise(RuntimeError, "frozen during comparison") {ary.sort!}