diff --git a/ChangeLog b/ChangeLog
index be1a665e89..8b4a3f60ec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,7 @@ Wed Nov 28 16:59:12 2012  Koichi Sasada  <ko1@atdot.net>
 
 	* proc.c: remove Proc#== and Proc#eql?.
 	  Proc objects compared with thier object ids.
+	  [Bug #4559]
 
 	* test/ruby/test_proc.rb: remove related test.