diff --git a/taiga/auth/services.py b/taiga/auth/services.py
index 1f3c4640..5e22b4bc 100644
--- a/taiga/auth/services.py
+++ b/taiga/auth/services.py
@@ -87,7 +87,7 @@ def get_membership_by_token(token:str):
     is raised.
     """
     membership_model = get_model("projects", "Membership")
-    qs = membership_model.objects.filter(user__isnull=True, token=token)
+    qs = membership_model.objects.filter(token=token)
     if len(qs) == 0:
         raise exc.NotFound("Token not matches any valid invitation.")
     return qs[0]
diff --git a/tests/integration/test_auth_api.py b/tests/integration/test_auth_api.py
index d9bc09b5..1774205a 100644
--- a/tests/integration/test_auth_api.py
+++ b/tests/integration/test_auth_api.py
@@ -61,7 +61,8 @@ def test_respond_201_if_domain_allows_public_registration(client, register_form)
     })
 
     response = client.post(reverse("auth-register"), register_form)
-    assert response.status_code == 201
+
+    assert response.status_code == 201, response.data
 
 
 def test_response_200_in_registration_with_github_account(client):