diff -r 160fd3a40072 Lib/test/test_tarfile.py
--- a/Lib/test/test_tarfile.py	Sat Apr 05 21:53:18 2014 +0200
+++ b/Lib/test/test_tarfile.py	Sat Apr 05 22:23:18 2014 +0200
@@ -2139,7 +2139,9 @@
     def test_open_fobj_integer_name(self):
         import tempfile
         with tempfile.TemporaryFile() as fobj:
-            tarfile.open(fileobj=fobj, mode='w')
+            for mode in ['', 'gz', 'bz2', 'xz']:
+                for sep in ['|', ':']:
+                    tarfile.open(fileobj=fobj, mode=('w' + sep + mode))
 
 
 def setUpModule():