diff --git a/requirements-testing.txt b/requirements-testing.txt
index f583651..5ef218a 100644
--- a/requirements-testing.txt
+++ b/requirements-testing.txt
@@ -1,2 +1,2 @@
 -r requirements.txt
-pytest==2.9.2
+pytest==5.3.5
diff --git a/rest_framework_sso/keys.py b/rest_framework_sso/keys.py
index b260398..2d64874 100644
--- a/rest_framework_sso/keys.py
+++ b/rest_framework_sso/keys.py
@@ -1,9 +1,9 @@
 # coding: utf-8
 import os
+import six
 
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives.serialization import load_pem_private_key, load_pem_public_key
-from django.utils import six
 from jwt.exceptions import InvalidKeyError
 
 from rest_framework_sso.settings import api_settings
diff --git a/rest_framework_sso/models.py b/rest_framework_sso/models.py
index 8a415f1..bb4ecb7 100644
--- a/rest_framework_sso/models.py
+++ b/rest_framework_sso/models.py
@@ -2,11 +2,16 @@
 from __future__ import absolute_import, unicode_literals
 
 import uuid
+import six
 
 from django.conf import settings
 from django.db import models
-from django.utils import six
-from django.utils.encoding import python_2_unicode_compatible
+
+try:
+    from django.utils.encoding import python_2_unicode_compatible as smart_text
+except ImportError:
+    from django.utils.encoding import smart_text
+
 from django.utils.translation import ugettext_lazy as _
 
 # Prior to Django 1.5, the AUTH_USER_MODEL setting does not exist.
@@ -22,7 +27,7 @@
 AUTH_USER_MODEL = getattr(settings, "AUTH_USER_MODEL", "auth.User")
 
 
-@python_2_unicode_compatible
+@smart_text
 class SessionToken(models.Model):
     """
     The default session token model.
diff --git a/rest_framework_sso/utils.py b/rest_framework_sso/utils.py
index 9f390fc..1d9c7a5 100644
--- a/rest_framework_sso/utils.py
+++ b/rest_framework_sso/utils.py
@@ -1,12 +1,14 @@
 # coding: utf-8
 from __future__ import absolute_import, unicode_literals
 
+import six
+import jwt
+
 from datetime import datetime
 
-import jwt
 from django.contrib.auth import get_user_model
 from django.core.serializers.json import DjangoJSONEncoder
-from django.utils import six, timezone
+from django.utils import timezone
 from django.utils.translation import gettext_lazy as _
 from jwt.exceptions import MissingRequiredClaimError, InvalidIssuerError, InvalidTokenError
 from rest_framework import exceptions
diff --git a/runtests.sh b/runtests.sh
index 63cc30e..2b58479 100755
--- a/runtests.sh
+++ b/runtests.sh
@@ -1,2 +1,2 @@
 #!/usr/bin/env bash
-DJANGO_SETTINGS_MODULE='tests.settings' py.test tests
+DJANGO_SETTINGS_MODULE='tests.settings' pytest tests
diff --git a/tests/test_keys.py b/tests/test_keys.py
index 5a9a588..e65a375 100644
--- a/tests/test_keys.py
+++ b/tests/test_keys.py
@@ -1,9 +1,9 @@
 # coding: utf-8
 from __future__ import absolute_import, unicode_literals
+import six
 
 from cryptography.hazmat.backends.openssl.rsa import _RSAPrivateKey, _RSAPublicKey
 from django.test import TestCase
-from django.utils import six
 from jwt.exceptions import InvalidKeyError
 
 from rest_framework_sso import keys