parsing of timezone differs between os x and windows

When I run this on OS X, with Python 3.3.2, I get a datetime with the expected timezone (Central Daylight Time):

>>> t = parser.parse("Jul 25, 2013 20:21 CDT")
>>> d = t.strftime("%Y%m%dT%H%M%S%z")
>>> print(d)
20130725T202100-0500
>>>

When I run this on Windows 7, also Python 3.3.2, I get a datetime without a timezone:

>>> t = parser.parse("Jul 25, 2013 20:21 CDT")
>>> d = t.strftime("%Y%m%dT%H%M%S%z")
>>> print(d)
20130725T202100
>>>

is this a problem with the Windows timezone info, or a problem with dateutil on Windows?