diff --git a/marietje/marietje/models.py b/marietje/marietje/models.py
index 6421c5d..a1f1ae1 100644
--- a/marietje/marietje/models.py
+++ b/marietje/marietje/models.py
@@ -1,10 +1,10 @@
 from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
 from django.contrib.auth.hashers import make_password
 from django.contrib.auth.models import PermissionsMixin
-from django.contrib.auth.validators import ASCIIUsernameValidator, UnicodeUsernameValidator
+from django.contrib.auth.validators import UnicodeUsernameValidator
 from django.core.mail import send_mail
 from django.db import models
-from django.utils import six, timezone
+from django.utils import timezone
 from django.utils.translation import ugettext_lazy as _
 
 from marietje.utils import get_first_queue
@@ -46,7 +46,7 @@ class UserManager(BaseUserManager):
 
 
 class User(AbstractBaseUser, PermissionsMixin):
-    username_validator = UnicodeUsernameValidator() if six.PY3 else ASCIIUsernameValidator()
+    username_validator = UnicodeUsernameValidator()
 
     username = models.CharField(
         _('username'),
diff --git a/requirements-production.txt b/requirements-production.txt
index e3cb23b..790a3ae 100644
--- a/requirements-production.txt
+++ b/requirements-production.txt
@@ -1,5 +1,5 @@
 setuptools
-django==2.1
+django>=2.2,<2.3
 mysqlclient
 https://projects.unbit.it/downloads/uwsgi-lts.tar.gz
 mutagen
diff --git a/requirements.txt b/requirements.txt
index cff865b..0900ae6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-django
+django>=2.2,<2.3
 mutagen
 argon2-cffi
 prometheus_client