diff --git a/oidc_provider/lib/utils/common.py b/oidc_provider/lib/utils/common.py
index 16673de..b7a6676 100644
--- a/oidc_provider/lib/utils/common.py
+++ b/oidc_provider/lib/utils/common.py
@@ -1,9 +1,5 @@
-import datetime
-import time
-
 from django.core.urlresolvers import reverse
 from django.http import HttpResponse
-from django.utils import timezone
 
 from oidc_provider import settings
 
@@ -102,19 +98,3 @@ def default_idtoken_processing_hook(id_token, user):
     :rtype dict
     """
     return id_token
-
-def to_timestamp(dt):
-    """
-    Convert a datetime to an integer timestamp.
-
-    Inspired from Py3 code, can be replaced by ``int(dt.timestamp())``
-    when Py2 is not supported anymore.
-
-    Note: we assume the timezone of naive datetimes is the one of the
-    system, not settings.TIME_ZONE as this setting may not have been
-    set by the user.
-    """
-    if timezone.is_aware(dt):
-        return int((dt - datetime.datetime(1970, 1, 1, tzinfo=timezone.utc)).total_seconds())
-    else:
-        return int(time.mktime(dt.timetuple()))
diff --git a/oidc_provider/lib/utils/token.py b/oidc_provider/lib/utils/token.py
index df3befa..7c06c00 100644
--- a/oidc_provider/lib/utils/token.py
+++ b/oidc_provider/lib/utils/token.py
@@ -1,4 +1,5 @@
 from datetime import timedelta
+import time
 import uuid
 
 from Cryptodome.PublicKey.RSA import importKey
@@ -8,7 +9,7 @@ from jwkest.jwk import SYMKey
 from jwkest.jws import JWS
 from jwkest.jwt import JWT
 
-from oidc_provider.lib.utils.common import get_issuer, to_timestamp
+from oidc_provider.lib.utils.common import get_issuer
 from oidc_provider.models import (
     Code,
     RSAKey,
@@ -29,10 +30,10 @@ def create_id_token(user, aud, nonce='', at_hash='', request=None, scope=[]):
 
     # Convert datetimes into timestamps.
     now = timezone.now()
-    iat_time = to_timestamp(now)
-    exp_time = to_timestamp(now + timedelta(seconds=expires_in))
+    iat_time = int(time.mktime(now.timetuple()))
+    exp_time = int(time.mktime((now + timedelta(seconds=expires_in)).timetuple()))
     user_auth_time = user.last_login or user.date_joined
-    auth_time = to_timestamp(user_auth_time)
+    auth_time = int(time.mktime(user_auth_time.timetuple()))
 
     dic = {
         'iss': get_issuer(request=request),
diff --git a/oidc_provider/tests/test_utils.py b/oidc_provider/tests/test_utils.py
index dea523a..32bdf8d 100644
--- a/oidc_provider/tests/test_utils.py
+++ b/oidc_provider/tests/test_utils.py
@@ -1,10 +1,6 @@
-import datetime
-
 from django.test import TestCase
-from django.utils import timezone
-from django.utils import six
 
-from oidc_provider.lib.utils.common import get_issuer, to_timestamp
+from oidc_provider.lib.utils.common import get_issuer
 
 
 class Request(object):
@@ -46,13 +42,3 @@ class CommonTest(TestCase):
         self.assertEqual(get_issuer(site_url='http://127.0.0.1:9000',
                                     request=request),
                          'http://127.0.0.1:9000/openid')
-
-    def test_to_timestamp(self):
-        if not six.PY2:
-            naive_dt = datetime.datetime.now()
-            self.assertEqual(to_timestamp(naive_dt), int(naive_dt.timestamp()))
-
-        aware_dt = datetime.datetime(2016, 3, 2, 14, 2, 6, 123, timezone.utc)
-        self.assertEqual(to_timestamp(aware_dt), 1456927326)
-        if not six.PY2:
-            self.assertEqual(to_timestamp(aware_dt), int(aware_dt.timestamp()))