diff --git a/ChangeLog b/ChangeLog
index c6016b6d3f..b0238057d3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jun 27 09:57:02 2011  Koichi Sasada  <ko1@atdot.net>
+
+	* thread_pthread.c (rb_thread_create_timer_thread): 
+	  Fixes missing initialization of oflags.
+
 Mon Jun 27 09:07:42 2011  Koichi Sasada  <ko1@atdot.net>
 
 	* thread_pthread.c: Stop polling in the timer thread when there are
diff --git a/thread_pthread.c b/thread_pthread.c
index f1137ec550..be10a190cf 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1137,6 +1137,7 @@ rb_thread_create_timer_thread(void)
 	    {
 		int oflags;
 #if defined(O_NONBLOCK)
+		oflags = fcntl(timer_thread_pipe[1], F_GETFL);
 		oflags |= O_NONBLOCK;
 		fcntl(timer_thread_pipe[1], F_SETFL, oflags);
 #endif /* defined(O_NONBLOCK) */