diff --git a/ChangeLog b/ChangeLog
index 03928d5e49..55f77aecef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat May  7 12:41:04 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+	fix mutex deadlock test hang-up.
+
+	* thread_win32.c (abs_timespec_to_timeout_ms): fix 1000x calculation
+	  mistake. (ie fix hang-up native_cond_timedwait())
+
 Sat May  7 03:14:13 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	sleep_cond use monotonic time if possible.
diff --git a/thread_win32.c b/thread_win32.c
index 80c3890975..6c7e0d2669 100644
--- a/thread_win32.c
+++ b/thread_win32.c
@@ -471,7 +471,7 @@ abs_timespec_to_timeout_ms(struct timespec *ts)
 
     gettimeofday(&now, NULL);
     tv.tv_sec = ts->tv_sec;
-    tv.tv_usec = ts->tv_nsec;
+    tv.tv_usec = ts->tv_nsec / 1000;
 
     if (!rb_w32_time_subtract(&tv, &now))
 	return 0;