diff --git a/ChangeLog b/ChangeLog
index a582317205..643c4ed309 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jun 16 18:52:47 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/thwait.rb (ThreadsWait): Exception2MessageMapper no longer has
+	  extend_to method.  [ruby-core:17267]
+
 Mon Jun 16 14:46:25 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/e2mmap.rb (E2MM.def_e2message): typo.
diff --git a/lib/thwait.rb b/lib/thwait.rb
index a6a0104d29..029b259157 100644
--- a/lib/thwait.rb
+++ b/lib/thwait.rb
@@ -53,7 +53,7 @@ require "e2mmap.rb"
 class ThreadsWait
   RCS_ID='-$Id: thwait.rb,v 1.3 1998/06/26 03:19:34 keiju Exp keiju $-'
   
-  Exception2MessageMapper.extend_to(binding)
+  extend Exception2MessageMapper
   def_exception("ErrNoWaitingThread", "No threads for waiting.")
   def_exception("ErrNoFinishedThread", "No finished threads.")