diff -r eee959fee5f5 Lib/test/test_sys.py
--- a/Lib/test/test_sys.py	Sat May 07 21:13:50 2016 +0300
+++ b/Lib/test/test_sys.py	Fri May 13 21:03:55 2016 +0200
@@ -10,6 +10,7 @@
 import gc
 import sysconfig
 import platform
+import locale
 
 # count the number of test runs, used to create unique
 # strings to intern in test_intern()
@@ -628,6 +629,12 @@
     @unittest.skipUnless(test.support.FS_NONASCII,
                          'requires OS support of non-ASCII encodings')
     def test_ioencoding_nonascii(self):
+        try:
+            with open(os.devnull, 'w') as f:
+                print(test.support.FS_NONASCII, file=f)
+        except UnicodeEncodeError:
+            self.skipTest('preferred encoding set to "%s"' %
+                          locale.getpreferredencoding())
         env = dict(os.environ)
 
         env["PYTHONIOENCODING"] = ""