diff --git a/passbook/providers/app_gw/forms.py b/passbook/providers/app_gw/forms.py
index d806e9d9d..ad4c7fc60 100644
--- a/passbook/providers/app_gw/forms.py
+++ b/passbook/providers/app_gw/forms.py
@@ -16,9 +16,9 @@ class ApplicationGatewayProviderForm(forms.ModelForm):
                 client_id=generate_client_id(), client_secret=generate_client_secret()
             )
         self.instance.client.name = self.instance.name
-        self.instance.client.response_types.set([ResponseType.objects.get_by_natural_key(
-            "code"
-        )])
+        self.instance.client.response_types.set(
+            [ResponseType.objects.get_by_natural_key("code")]
+        )
         self.instance.client.redirect_uris = [
             f"http://{self.instance.external_host}/oauth2/callback",
             f"https://{self.instance.external_host}/oauth2/callback",