diff --git a/django_auth_adfs/backend.py b/django_auth_adfs/backend.py
index 475b807..8968601 100644
--- a/django_auth_adfs/backend.py
+++ b/django_auth_adfs/backend.py
@@ -123,7 +123,7 @@ def create_user(self, claims):
         username_claim = settings.USERNAME_CLAIM
         usermodel = get_user_model()
 
-        if claims.get(username_claim, None) is None:
+        if not claims.get(username_claim):
             logger.error("User claim's doesn't have the claim '%s' in his claims: %s" % (username_claim, claims))
             raise PermissionDenied
         userdata = {usermodel.USERNAME_FIELD: claims[username_claim]}