diff --git a/oidc_provider/lib/utils/token.py b/oidc_provider/lib/utils/token.py
index 7c06c00..3f0d2e9 100644
--- a/oidc_provider/lib/utils/token.py
+++ b/oidc_provider/lib/utils/token.py
@@ -3,7 +3,7 @@ import time
 import uuid
 
 from Cryptodome.PublicKey.RSA import importKey
-from django.utils import timezone
+from django.utils import dateformat, timezone
 from jwkest.jwk import RSAKey as jwk_RSAKey
 from jwkest.jwk import SYMKey
 from jwkest.jws import JWS
@@ -29,11 +29,11 @@ def create_id_token(user, aud, nonce='', at_hash='', request=None, scope=[]):
     expires_in = settings.get('OIDC_IDTOKEN_EXPIRE')
 
     # Convert datetimes into timestamps.
-    now = timezone.now()
-    iat_time = int(time.mktime(now.timetuple()))
-    exp_time = int(time.mktime((now + timedelta(seconds=expires_in)).timetuple()))
+    now = int(time.time())
+    iat_time = now
+    exp_time = int(now + expires_in)
     user_auth_time = user.last_login or user.date_joined
-    auth_time = int(time.mktime(user_auth_time.timetuple()))
+    auth_time = int(dateformat.format(user_auth_time, 'U'))
 
     dic = {
         'iss': get_issuer(request=request),
diff --git a/oidc_provider/tests/test_token_endpoint.py b/oidc_provider/tests/test_token_endpoint.py
index de7972e..7660240 100644
--- a/oidc_provider/tests/test_token_endpoint.py
+++ b/oidc_provider/tests/test_token_endpoint.py
@@ -1,5 +1,5 @@
-from datetime import timedelta
 import json
+import time
 import uuid
 
 from base64 import b64encode
@@ -15,7 +15,6 @@ from django.test import (
     override_settings,
 )
 from django.test import TestCase
-from django.utils import timezone
 from jwkest.jwk import KEYS
 from jwkest.jws import JWS
 from jwkest.jwt import JWT
@@ -164,9 +163,9 @@ class TokenTestCase(TestCase):
         # Retrieve refresh token
         code = self._create_code()
         post_data = self._auth_code_post_data(code=code.code)
-        real_now = timezone.now
-        with patch('oidc_provider.lib.utils.token.timezone.now') as now:
-            now.return_value = real_now()
+        start_time = time.time()
+        with patch('oidc_provider.lib.utils.token.time.time') as time_func:
+            time_func.return_value = start_time
             response = self._post_request(post_data)
 
         response_dic1 = json.loads(response.content.decode('utf-8'))
@@ -174,8 +173,8 @@ class TokenTestCase(TestCase):
 
         # Use refresh token to obtain new token
         post_data = self._refresh_token_post_data(response_dic1['refresh_token'])
-        with patch('oidc_provider.lib.utils.token.timezone.now') as now:
-            now.return_value = real_now() + timedelta(minutes=10)
+        with patch('oidc_provider.lib.utils.token.time.time') as time_func:
+            time_func.return_value = start_time + 600
             response = self._post_request(post_data)
 
         response_dic2 = json.loads(response.content.decode('utf-8'))
@@ -189,6 +188,8 @@ class TokenTestCase(TestCase):
         self.assertEqual(id_token1['iss'], id_token2['iss'])
         self.assertEqual(id_token1['sub'], id_token2['sub'])
         self.assertNotEqual(id_token1['iat'], id_token2['iat'])
+        self.assertEqual(id_token1['iat'], int(start_time))
+        self.assertEqual(id_token2['iat'], int(start_time + 600))
         self.assertEqual(id_token1['aud'], id_token2['aud'])
         self.assertEqual(id_token1['auth_time'], id_token2['auth_time'])
         self.assertEqual(id_token1.get('azp'), id_token2.get('azp'))
diff --git a/oidc_provider/tests/test_utils.py b/oidc_provider/tests/test_utils.py
index 32bdf8d..fd09c40 100644
--- a/oidc_provider/tests/test_utils.py
+++ b/oidc_provider/tests/test_utils.py
@@ -1,6 +1,12 @@
+import time
+from datetime import datetime
+
 from django.test import TestCase
+from django.utils import timezone
 
 from oidc_provider.lib.utils.common import get_issuer
+from oidc_provider.lib.utils.token import create_id_token
+from oidc_provider.tests.app.utils import create_fake_user
 
 
 class Request(object):
@@ -42,3 +48,31 @@ 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 timestamp_to_datetime(timestamp):
+    tz = timezone.get_current_timezone()
+    return datetime.fromtimestamp(timestamp, tz=tz)
+
+
+class TokenTest(TestCase):
+    def setUp(self):
+        self.user = create_fake_user()
+
+    def test_create_id_token(self):
+        start_time = int(time.time())
+        login_timestamp = start_time - 1234
+        self.user.last_login = timestamp_to_datetime(login_timestamp)
+        id_token_data = create_id_token(self.user, aud='test-aud')
+        iat = id_token_data['iat']
+        self.assertEqual(type(iat), int)
+        self.assertGreaterEqual(iat, start_time)
+        self.assertLessEqual(iat - start_time, 5)  # Can't take more than 5 s
+        self.assertEqual(id_token_data, {
+            'aud': 'test-aud',
+            'auth_time': login_timestamp,
+            'exp': iat + 600,
+            'iat': iat,
+            'iss': 'http://localhost:8000/openid',
+            'sub': str(self.user.id),
+        })