diff --git a/authens/tests/test_backend.py b/authens/tests/test_backend.py
index a0d06b6..3c1556f 100644
--- a/authens/tests/test_backend.py
+++ b/authens/tests/test_backend.py
@@ -16,11 +16,11 @@ class TestCASBackend(TestCase):
         UserModel.objects.create(username="toto2")
         backend = ENSCASBackend()
         for _ in range(10):
-            username = backend.get_free_username("toto")
+            username = backend.get_free_username("toto", None)
             self.assertFalse(UserModel.objects.filter(username=username).exists())
             UserModel.objects.create(username=username)
         for _ in range(10):
-            username = backend.get_free_username("tutu")
+            username = backend.get_free_username("tutu", None)
             self.assertFalse(UserModel.objects.filter(username=username).exists())
             UserModel.objects.create(username=username)