diff --git a/Lib/datetime.py b/Lib/datetime.py
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1505,16 +1505,9 @@
                 gmtoff = localtm.tm_gmtoff
                 zone = localtm.tm_zone
             except AttributeError:
-                # Compute UTC offset and compare with the value implied
-                # by tm_isdst.  If the values match, use the zone name
-                # implied by tm_isdst.
                 delta = local - datetime(*_time.gmtime(ts)[:6])
-                dst = _time.daylight and localtm.tm_isdst > 0
-                gmtoff = -(_time.altzone if dst else _time.timezone)
-                if delta == timedelta(seconds=gmtoff):
-                    tz = timezone(delta, _time.tzname[dst])
-                else:
-                    tz = timezone(delta)
+                zone = _time.strftime('%Z', localtm)
+                tz = timezone(delta, zone)
             else:
                 tz = timezone(timedelta(seconds=gmtoff), zone)