diff --git a/acme/acme/client.py b/acme/acme/client.py
index 6a4457430..470ffc41f 100644
--- a/acme/acme/client.py
+++ b/acme/acme/client.py
@@ -262,19 +262,14 @@ class Client(object):  # pylint: disable=too-many-instance-attributes
         try:
             seconds = int(retry_after)
         except ValueError:
-            # pylint: disable=no-member
             when = parsedate_tz(retry_after)
-            try:
-                year = when[0] # raises TypeError if t is None
-                # py26: Handle two-digit years -- but any server that thinks
-                # "retry after 99" means "come back after 1999" is.. deprecated
-                if year >= 0 and year < 100:
-                    when = [year + 2000] + list(when[1:]) #  pragma: no cover
-                tzone = when[-1] if when[-1] else 0
-                # raises ValueError/OverflowError
-                return datetime.datetime(*when[:7]) - datetime.timedelta(tzone)
-            except (TypeError, ValueError, OverflowError):
-                seconds = default
+            if when is not None:
+                try:
+                    tz_secs = datetime.timedelta(when[-1] if when[-1] else 0)
+                    return datetime.datetime(*when[:7]) - tz_secs
+                except (ValueError, OverflowError):
+                    pass
+            seconds = default
 
         return datetime.datetime.now() + datetime.timedelta(seconds=seconds)
 
diff --git a/acme/acme/client_test.py b/acme/acme/client_test.py
index dee78910f..9abc69c7c 100644
--- a/acme/acme/client_test.py
+++ b/acme/acme/client_test.py
@@ -194,10 +194,6 @@ class ClientTest(unittest.TestCase):
         self.assertEqual(
             datetime.datetime(1999, 12, 31, 23, 59, 59),
             self.client.retry_after(response=self.response, default=10))
-        self.response.headers['Retry-After'] = 'Fri, 31-Dec-17 23:59:59 GMT'
-        self.assertEqual(
-            datetime.datetime(2017, 12, 31, 23, 59, 59),
-            self.client.retry_after(response=self.response, default=10))
 
     @mock.patch('acme.client.datetime')
     def test_retry_after_invalid(self, dt_mock):