diff --git a/ChangeLog b/ChangeLog
index 032efbac96..71dc12b322 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Feb 24 15:41:22 2007  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* lib/thread.rb: do not redefine Mutex#synchronize.
+
 Sat Feb 24 15:14:02 2007  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* lib/monitor.rb: rewritten using Mutex/ConditionVariable.
diff --git a/lib/thread.rb b/lib/thread.rb
index 11c9d5a1cc..96e7875bea 100644
--- a/lib/thread.rb
+++ b/lib/thread.rb
@@ -21,15 +21,6 @@ if $DEBUG
   Thread.abort_on_exception = true
 end
 
-class Mutex
-  def synchronize
-    self.lock
-    yield
-  ensure
-    self.unlock
-  end
-end
-
 # 
 # ConditionVariable objects augment class Mutex. Using condition variables,
 # it is possible to suspend while in the middle of a critical section until a