Index: Lib/calendar.py
===================================================================
--- Lib/calendar.py	(revision 81989)
+++ Lib/calendar.py	(working copy)
@@ -587,17 +587,14 @@
 
 
 EPOCH = 1970
-_EPOCH_ORD = datetime.date(EPOCH, 1, 1).toordinal()
+_EPOCH_DATETIME = datetime.datetime(EPOCH, 1, 1)
+_SECOND = datetime.timedelta(seconds=1)
 
-
 def timegm(tuple):
     """Unrelated but handy function to calculate Unix timestamp from GMT."""
-    year, month, day, hour, minute, second = tuple[:6]
-    days = datetime.date(year, month, 1).toordinal() - _EPOCH_ORD + day - 1
-    hours = days*24 + hour
-    minutes = hours*60 + minute
-    seconds = minutes*60 + second
-    return seconds
+    return (datetime.datetime(*tuple[:5]) +
+            datetime.timedelta(seconds=tuple[5]) -
+            _EPOCH_DATETIME) / _SECOND
 
 
 def main(args):