Index: Lib/test/test_os.py
===================================================================
--- Lib/test/test_os.py	(revision 72347)
+++ Lib/test/test_os.py	(working copy)
@@ -8,6 +8,7 @@
 import warnings
 import sys
 import shutil
+import unicodedata
 from test import support
 
 # Tests creating TESTFN
@@ -701,7 +702,10 @@
                 self.assertRaises(OverflowError, os.setregid, 0, 1<<32)
 
     class Pep383Tests(unittest.TestCase):
-        filenames = [b'foo\xf6bar', 'foo\xf6bar'.encode("utf-8")]
+        if sys.platform == 'darwin':
+            filenames = ['foo\xf6bar'.encode("utf-8")]
+        else:
+            filenames = [b'foo\xf6bar', 'foo\xf6bar'.encode("utf-8")]
 
         def setUp(self):
             self.fsencoding = sys.getfilesystemencoding()
@@ -720,8 +724,12 @@
             sys.setfilesystemencoding(self.fsencoding)
 
         def test_listdir(self):
-            expected = set(self.unicodefn)
-            found = set(os.listdir(support.TESTFN))
+            # Some filesystems (e.g. HFS+) yield NFD-normalized
+            # filenames, so normalize before comparing.
+            def normalize(s):
+                return unicodedata.normalize('NFD', s)
+            expected = set(normalize(s) for s in self.unicodefn)
+            found = set(normalize(s) for s in os.listdir(support.TESTFN))
             self.assertEquals(found, expected)
 
         def test_open(self):