diff --git a/requirements-dev.txt b/requirements-dev.txt
index 9998ce7..e6ef993 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -7,3 +7,4 @@ django-picklefield>=0.3.1
 requests_futures>=0.9.5
 django-bootstrap3>=5.4
 lxml>=3.4
+six>=1
diff --git a/requirements.txt b/requirements.txt
index 38096e1..937a0d0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,4 +4,4 @@ requests_futures>=0.9.5
 django-picklefield>=0.3.1
 django-bootstrap3>=5.4
 lxml>=3.4
-
+six>=1
diff --git a/setup.py b/setup.py
index a9826c7..5e90985 100644
--- a/setup.py
+++ b/setup.py
@@ -31,7 +31,7 @@ except pkg_resources.DistributionNotFound:
 
 setup(
     name='django-cas-server',
-    version='0.4.4',
+    version='0.5.0',
     packages=[
         'cas_server', 'cas_server.migrations',
         'cas_server.management', 'cas_server.management.commands'
@@ -67,7 +67,8 @@ setup(
     keywords=['django', 'cas', 'cas3', 'server', 'sso', 'single sign-on', 'authentication', 'auth'],
     install_requires=[
         django, 'requests >= 2.4', 'requests_futures >= 0.9.5',
-        'django-picklefield >= 0.3.1', django_bootstrap3, 'lxml >= 3.4'
+        'django-picklefield >= 0.3.1', django_bootstrap3, 'lxml >= 3.4',
+        'six >= 1'
     ],
     url="https://github.com/nitmir/django-cas-server",
     download_url="https://github.com/nitmir/django-cas-server/releases",