diff --git a/fail2ban/server/strptime.py b/fail2ban/server/strptime.py
index 68ff2f41..56f1c753 100644
--- a/fail2ban/server/strptime.py
+++ b/fail2ban/server/strptime.py
@@ -27,7 +27,7 @@ from .mytime import MyTime
 
 locale_time = LocaleTime()
 timeRE = TimeRE()
-FIXED_OFFSET_TZ_RE = re.compile(r'(?:Z|UTC|GMT)?([+-]\d{2}(?:\d{2}))?$')
+FIXED_OFFSET_TZ_RE = re.compile(r'(?:Z|UTC|GMT)?([+-]\d{2}(?::?\d{2})?)?$')
 
 def _getYearCentRE(cent=(0,3), distance=3, now=(MyTime.now(), MyTime.alternateNow)):
 	""" Build century regex for last year and the next years (distance).
@@ -108,8 +108,15 @@ def zone2offset(tz, dt):
 	dt: datetime instance for offset computation
 	"""
 	if isinstance(tz, basestring):
-		# [+-]1 * (hh*60 + mm)
-		return int(tz[0]+'1') * (int(tz[1:3])*60 + int(tz[3:5]))
+		if len(tz) <= 3: # short tz (hh only)
+			# [+-]hh --> [+-]hh*60
+			return int(tz)*60
+		if tz[3] != ':':
+			# [+-]hhmm --> [+-]1 * (hh*60 + mm)
+			return int(tz[0]+'1') * (int(tz[1:3])*60 + int(tz[3:5]))
+		else:
+			# [+-]hh:mm --> [+-]1 * (hh*60 + mm)
+			return int(tz[0]+'1') * (int(tz[1:3])*60 + int(tz[4:6]))
 	return tz
 
 def reGroupDictStrptime(found_dict, msec=False, default_tz=None):
@@ -202,11 +209,7 @@ def reGroupDictStrptime(found_dict, msec=False, default_tz=None):
 			if z in ("Z", "UTC", "GMT"):
 				tzoffset = 0
 			else:
-				tzoffset = int(z[1:3]) * 60 # Hours...
-				if len(z)>3:
-					tzoffset += int(z[-2:]) # ...and minutes
-				if z.startswith("-"):
-					tzoffset = -tzoffset
+				tzoffset = zone2offset(z, 0); # currently offset-based only
 		elif key == 'Z':
 			z = val
 			if z in ("UTC", "GMT"):
diff --git a/fail2ban/tests/datedetectortestcase.py b/fail2ban/tests/datedetectortestcase.py
index 6d728b5e..cbf1ac21 100644
--- a/fail2ban/tests/datedetectortestcase.py
+++ b/fail2ban/tests/datedetectortestcase.py
@@ -90,21 +90,31 @@ class DateDetectorTest(LogCaptureTestCase):
 		self.assertEqual(matchlog.group(1), 'Jan 23 21:59:59')
 
 	def testDefaultTimeZone(self):
-		log = "2017-01-23 15:00:00"
 		dd = self.datedetector
-		dd.default_tz='UTC+0300'; datelog, _ = dd.getTime(log)
-		# so in UTC, it was noon
-		self.assertEqual(datetime.datetime.utcfromtimestamp(datelog),
-				 datetime.datetime(2017, 1, 23, 12, 0, 0))
-
-		dd.default_tz='UTC'; datelog, _ = dd.getTime(log)
-		self.assertEqual(datetime.datetime.utcfromtimestamp(datelog),
-				 datetime.datetime(2017, 1, 23, 15, 0, 0))
-		self.assertEqual(dd.default_tz, 0); # utc == 0
-
-		dd.default_tz='UTC-0430'; datelog, _ = dd.getTime(log)
-		self.assertEqual(datetime.datetime.utcfromtimestamp(datelog),
-				 datetime.datetime(2017, 1, 23, 19, 30, 0))
+		dt = datetime.datetime
+		logdt = "2017-01-23 15:00:00"
+		dtUTC = dt(2017, 1, 23, 15, 0)
+		for tz, log, desired in (
+			('UTC+0300', logdt, dt(2017, 1, 23, 12, 0)), # so in UTC, it was noon
+			('UTC',      logdt, dtUTC), # UTC
+			('UTC-0430', logdt, dt(2017, 1, 23, 19, 30)),
+			('GMT+12',   logdt, dt(2017, 1, 23, 3, 0)),
+			(None,			 logdt, dt(2017, 1, 23, 14, 0)), # default CET in our test-framework
+			('UTC+0300', logdt+' GMT', dtUTC), # GMT wins
+			('UTC',      logdt+' GMT', dtUTC), # GMT wins
+			('UTC-0430', logdt+' GMT', dtUTC), # GMT wins
+			(None,			 logdt+' GMT', dtUTC), # GMT wins
+			('UTC',      logdt+' -1045', dt(2017, 1, 24, 1, 45)), # -1045 wins
+			(None,			 logdt+' -10:45', dt(2017, 1, 24, 1, 45)), # -1045 wins
+			('UTC',      logdt+' +0945', dt(2017, 1, 23, 5, 15)), # +0945 wins
+			(None,			 logdt+' +09:45', dt(2017, 1, 23, 5, 15)), # +0945 wins
+			(None,			 logdt+' Z', dtUTC), # Z wins (UTC)
+		):
+			logSys.debug('== test %r with TZ %r', log, tz)
+			dd.default_tz=tz; datelog, _ = dd.getTime(log)
+			val = dt.utcfromtimestamp(datelog)
+			self.assertEqual(val, desired,
+					 "wrong offset %r != %r by %r with TZ %r (%r)" % (val, desired, log, tz, dd.default_tz))
 
 		self.assertRaises(ValueError, setattr, dd, 'default_tz', 'WRONG-TZ')
 		dd.default_tz = None