diff --git a/src/oas/schema/formats.py b/src/oas/schema/formats.py
index 5689c00..8c2e32d 100644
--- a/src/oas/schema/formats.py
+++ b/src/oas/schema/formats.py
@@ -83,9 +83,11 @@ def parse_date(value):
 except ImportError:  # pragma: no cover
     pyrfc3339 = None
 else:
-    _register('date-time', 'string', raises=ValueError)(
-        functools.partial(pyrfc3339.parse, utc=True)
-    )
+
+    @_register('date-time', 'string', raises=ValueError)
+    def parse_date_time(value):
+        return pyrfc3339.parse(value, utc=True).replace(tzinfo=None)
+
 
 try:
     import rfc3986
diff --git a/tests/schema/test_formats.py b/tests/schema/test_formats.py
index a2a97fa..a793fec 100644
--- a/tests/schema/test_formats.py
+++ b/tests/schema/test_formats.py
@@ -9,37 +9,32 @@
 
 import jsonschema
 import pytest
-import pytz
 
 from oas.schema.formats import default_formats
 from oas.schema.formats import Formats
 
 
 @pytest.mark.parametrize(
-    'name,value,expected',
+    'name,value',
     [
-        ('int32', 0, None),
-        ('int32', -(2 ** 31), None),
-        ('int32', 2 ** 31 - 1, None),
-        ('int64', 0, None),
-        ('int64', -(2 ** 63), None),
-        ('int64', 2 ** 63 - 1, None),
-        ('byte', base64.b64encode(b'foo'), b'foo'),
-        ('binary', '010203', b'\x01\x02\x03'),
-        ('date', '2020-01-02', datetime.date(2020, 1, 2)),
-        (
-            'date-time',
-            '2020-01-02T03:04:05Z',
-            datetime.datetime(2020, 1, 2, 3, 4, 5, tzinfo=pytz.utc),
-        ),
-        ('uri', 'http://example.com', None),
-        ('uri', 'https://example.com', None),
-        ('uri', 'https://example.com/', None),
-        ('uri', 'https://example.com/path', None),
-        ('uri', 'https://example.com/path?query#segment', None),
+        ('int32', 0),
+        ('int32', -(2 ** 31)),
+        ('int32', 2 ** 31 - 1),
+        ('int64', 0),
+        ('int64', -(2 ** 63)),
+        ('int64', 2 ** 63 - 1),
+        ('byte', base64.b64encode(b'foo')),
+        ('binary', '010203'),
+        ('date', '2020-01-02'),
+        ('date-time', '2020-01-02T03:04:05Z'),
+        ('uri', 'http://example.com'),
+        ('uri', 'https://example.com'),
+        ('uri', 'https://example.com/'),
+        ('uri', 'https://example.com/path'),
+        ('uri', 'https://example.com/path?query#segment'),
     ],
 )
-def test_default_checker_success(name, value, expected):
+def test_default_checker_success(name, value):
     format_checker = default_formats.format_checker
     try:
         format_checker.check(value, name)
@@ -87,7 +82,12 @@ def test_default_checker_error(name, value):
         (
             'date-time',
             '2020-01-02T03:04:05Z',
-            datetime.datetime(2020, 1, 2, 3, 4, 5, tzinfo=pytz.utc),
+            datetime.datetime(2020, 1, 2, 3, 4, 5),
+        ),
+        (
+            'date-time',
+            '2020-01-02T03:04:05+09:00',
+            datetime.datetime(2020, 1, 1, 18, 4, 5),
         ),
         ('uri', 'http://example.com', None),
         ('uri', 'https://example.com', None),