diff --git a/ChangeLog b/ChangeLog
index 5586420d45..1985c52ea2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Mon Oct  5 20:39:32 2015  Benoit Daloze  <eregontp@gmail.com>
+
+	* test/ruby/test_thread.rb: fix potential race condition.
+	  The thread could have a "sleep" status because it tries
+	  to acquire the mutex, but does not have it yet.
+
 Mon Oct  5 15:39:30 2015  Zachary Scott  <zzak@ruby-lang.org>
 
 	* numeric.c: [DOC] Overview for Numeric class by Joe Corcoran
diff --git a/test/ruby/test_thread.rb b/test/ruby/test_thread.rb
index eaf65ae86d..e60da4f120 100644
--- a/test/ruby/test_thread.rb
+++ b/test/ruby/test_thread.rb
@@ -914,9 +914,8 @@ q.pop
         sleep
       }
 
-      Thread.pass until th.status == "sleep"
-      # acquired another thread.
-      assert_equal(mutex.locked?, true)
+      # acquired by another thread.
+      Thread.pass until mutex.locked?
       assert_equal(mutex.owned?, false)
     ensure
       th.kill if th