The datetime docs (http://docs.python.org/library/datetime.html) have a code sample which doesn't follow advice from another part of the same page. First, here's the advice: Special requirement for pickling: A tzinfo<http://docs.python.org/library/datetime.html#datetime.tzinfo> subclass must have an __init__()<http://docs.python.org/reference/datamodel.html#object.__init__> method that can be called with no arguments, else it can be pickled but possibly not unpickled again. This is a technical requirement that may be relaxed in the future. Here's the sample: class FixedOffset(tzinfo): """Fixed offset in minutes east from UTC.""" def __init__(self, offset, name): self.__offset = timedelta(minutes = offset) self.__name = name def utcoffset(self, dt): return self.__offset This sample, if It's following the page's own advice, should have an __init__ method to support pickling which has no required parameters (except self, of course). Something like this: def __init__(self, offset_hours=0, offset_minutes=0, name=''): Of course, this may not be the right behavior either (e.g. might want to create a default name for the time zone based on hours & minutes) but at least by specifying default parameter values you avoid hard-to-troubleshoot exceptions at runtime like your existing sample did for me. :-) Thanks! Justin Grant jgrant@splunk.com<mailto:jgrant@splunk.com> | +1 415 848 8578 Splunk | Product Management