diff --git a/rest_auth/serializers.py b/rest_auth/serializers.py
index 5f3541d..817e561 100644
--- a/rest_auth/serializers.py
+++ b/rest_auth/serializers.py
@@ -81,7 +81,7 @@ class LoginSerializer(serializers.Serializer):
             # Authentication without using allauth
             if email:
                 try:
-                    username = UserModel.objects.get(email__iexact=email).username
+                    username = UserModel.objects.get(email__iexact=email).get_username()
                 except UserModel.DoesNotExist:
                     pass