diff --git a/ChangeLog b/ChangeLog
index 05c899f6e0..2b6a1abca4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Sep  6 08:10:44 2014  Eric Wong  <e@80x24.org>
+
+	* test/ruby/test_io.rb (test_readpartial_locktmp): use IO#nonblock=
+	  Old fcntl invocation may drop necessary flags on some platforms.
+
 Sat Sep  6 07:46:51 2014  Eric Wong  <e@80x24.org>
 
 	* test/ruby/test_io.rb (test_readpartial_locktmp): avoid EBADF
diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 0afcbbac0c..c3544b930a 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -2867,7 +2867,7 @@ End
     th = nil
     with_pipe do |r,w|
       begin
-        r.fcntl(Fcntl::F_SETFL, Fcntl::O_NONBLOCK)
+        r.nonblock = true
         th = Thread.new {r.readpartial(100, buf)}
 
         Thread.pass until th.stop?