diff --git a/h/services/mention.py b/h/services/mention.py
index 512508cf571..6d5e3bcc528 100644
--- a/h/services/mention.py
+++ b/h/services/mention.py
@@ -33,7 +33,9 @@ def update_mentions(self, annotation: Annotation) -> None:
         if mentioning_user.nipsa:
             return
 
-        mentioned_userids = OrderedDict.fromkeys(self._parse_userids(annotation.text)).keys()
+        mentioned_userids = OrderedDict.fromkeys(
+            self._parse_userids(annotation.text)
+        ).keys()
         mentioned_users = self._user_service.fetch_all(mentioned_userids)
         self._session.execute(
             delete(Mention).where(Mention.annotation_id == annotation.id)
diff --git a/tests/unit/h/services/mention_test.py b/tests/unit/h/services/mention_test.py
index 30336820762..0f894be8f7b 100644
--- a/tests/unit/h/services/mention_test.py
+++ b/tests/unit/h/services/mention_test.py
@@ -68,7 +68,9 @@ def test_update_mentions_with_private_annotation(self, service, annotation):
 
         assert len(annotation.mentions) == 0
 
-    def test_update_mentions_with_own_mention(self, service, annotation, user_service, mentioning_user):
+    def test_update_mentions_with_own_mention(
+        self, service, annotation, user_service, mentioning_user
+    ):
         user_service.fetch_all.return_value = [mentioning_user]
 
         service.update_mentions(annotation)