diff --git a/ChangeLog b/ChangeLog
index cf5dda5199..7fad7a8fe3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu Jun 30 00:49:53 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* thread.c (rb_thread_wakeup): change RDoc sample code. The old
+	  example is buggy and may not display anything by a race.
+	  The patch is suggested by Heesob Parrk <phasis@gmail.com>.
+	  Thank you! [Bug #3606][ruby-core:31454]
+
 Thu Jun 30 00:43:33 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* thread.c (rb_thread_run): change RDoc. The old example is buggy
diff --git a/thread.c b/thread.c
index 0f7bce4e1c..894c7909ea 100644
--- a/thread.c
+++ b/thread.c
@@ -1589,7 +1589,9 @@ rb_thread_exit(void)
  *  I/O, however). Does not invoke the scheduler (see <code>Thread#run</code>).
  *
  *     c = Thread.new { Thread.stop; puts "hey!" }
+ *     sleep 0.1 while c.status!='sleep'
  *     c.wakeup
+ *     c.join
  *
  *  <em>produces:</em>
  *