diff --git a/ChangeLog b/ChangeLog
index d117279396..bb05a7ae8a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Nov  2 14:43:48 2009  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* thread_pthread.c (native_stop_timer_thread): delay joinning timer
+	  thread after unlocking mutex.
+
 Mon Nov  2 13:31:14 2009  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* thread_pthread.c (native_stop_timer_thread): need to join timer thread
diff --git a/thread_pthread.c b/thread_pthread.c
index e82777d68e..2273d2062c 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -814,9 +814,11 @@ native_stop_timer_thread(void)
     stopped = --system_working <= 0;
     if (stopped) {
 	native_cond_signal(&timer_thread_cond);
-	native_thread_join(timer_thread_id);
     }
     native_mutex_unlock(&timer_thread_lock);
+    if (stopped) {
+	native_thread_join(timer_thread_id);
+    }
     return stopped;
 }