diff --git a/modoboa/transport/api/v2/tests.py b/modoboa/transport/api/v2/tests.py
new file mode 100644
index 000000000..790ba2ea6
--- /dev/null
+++ b/modoboa/transport/api/v2/tests.py
@@ -0,0 +1,16 @@
+"""API v2 tests."""
+
+from django.urls import reverse
+
+from modoboa.lib.tests import ModoAPITestCase
+
+
+class TransportViewSetTestCase(ModoAPITestCase):
+
+    def test_list(self):
+        url = reverse("v2:transport-list")
+        resp = self.client.get(url)
+        self.assertEqual(resp.status_code, 200)
+        backends = resp.json()
+        self.assertEqual(len(backends), 1)
+        self.assertEqual(backends[0]["name"], "relay")
diff --git a/modoboa/transport/api/v2/viewsets.py b/modoboa/transport/api/v2/viewsets.py
index 59cd4cdca..28d2b005f 100644
--- a/modoboa/transport/api/v2/viewsets.py
+++ b/modoboa/transport/api/v2/viewsets.py
@@ -20,6 +20,8 @@ class TransportViewSet(viewsets.ViewSet):
         all_settings = backends.manager.get_all_backend_settings()
         result = []
         for name, settings in all_settings.items():
-            serializer = serializers.TransportBackendSerializer({"name": name, "settings": settings})
+            serializer = serializers.TransportBackendSerializer(
+                {"name": name, "settings": settings}
+            )
             result.append(serializer.data)
         return response.Response(result)