diff --git a/pasn1.py b/pasn1.py
index f56ba11..b1e647a 100644
--- a/pasn1.py
+++ b/pasn1.py
@@ -364,6 +364,7 @@ class ASN1Coder(object):
 		return fun(data, pos + 1 + b, end)
 
 	def enc_datetime(self, obj, **kwargs):
+		obj = obj.astimezone(datetime.timezone.utc)
 		ts = obj.strftime('%Y%m%d%H%M%S')
 		if obj.microsecond:
 			ts += ('.%06d' % obj.microsecond).rstrip('0')
@@ -385,7 +386,7 @@ class ASN1Coder(object):
 				raise ValueError('invalid trailing zeros')
 		else:
 			fstr = '%Y%m%d%H%M%SZ'
-		return datetime.datetime.strptime(ts, fstr), end
+		return datetime.datetime.strptime(ts, fstr).replace(tzinfo=datetime.timezone.utc), end
 
 	def loads(self, data, pos=0, end=None, consume=False):
 		'''Load from data, starting at pos (optional), and ending
@@ -602,6 +603,30 @@ class TestCode(unittest.TestCase):
 		# XXX - add test to reject datetime w/ tzinfo, or that it
 		# handles it properly
 
+	def test_tzdate(self):
+		dlocal = datetime.datetime.now()
+		dutc = dlocal.astimezone(datetime.timezone.utc)
+		dts = dutc.timestamp()
+
+		# sanity check
+		self.assertEqual(dts, dlocal.timestamp())
+
+		# verify that the same datetime, but with different
+		# tzinfo, is serialized the same way
+		self.assertEqual(dumps(dlocal), dumps(dutc))
+
+		# that when dutc is read back
+		dround = loads(dumps(dutc))
+
+		# that it represents the same time
+		self.assertEqual(dround.timestamp(), dts)
+
+		# that when dlocal is read back
+		dround = loads(dumps(dlocal))
+
+		# that it represents the same time
+		self.assertEqual(dround.timestamp(), dts)
+
 	def test_dumps(self):
 		for i in [ None,
 		    True, False,
@@ -619,10 +644,10 @@ class TestCode(unittest.TestCase):
 		    {}, { 5: 10, 'adfkj': 34 },
 		    set(), set((1,2,3)),
 		    set((1,'sjlfdkj', None, float('inf'))),
-		    datetime.datetime.utcnow(),
-		    [ datetime.datetime.utcnow(), ' ' ],
-		    datetime.datetime.utcnow().replace(microsecond=0),
-		    datetime.datetime.utcnow().replace(microsecond=1000),
+		    datetime.datetime.utcnow().replace(tzinfo=datetime.timezone.utc),
+		    [ datetime.datetime.utcnow().replace(tzinfo=datetime.timezone.utc), ' ' ],
+		    datetime.datetime.utcnow().replace(microsecond=0, tzinfo=datetime.timezone.utc),
+		    datetime.datetime.utcnow().replace(microsecond=1000, tzinfo=datetime.timezone.utc),
 		    ]:
 			s = dumps(i)
 			o = loads(s)