diff --git a/passkey/db/__init__.py b/passkey/db/__init__.py
index 55e4258..fbe17fa 100644
--- a/passkey/db/__init__.py
+++ b/passkey/db/__init__.py
@@ -101,7 +101,9 @@ class DatabaseInterface(ABC):
         """Create a new user."""
 
     @abstractmethod
-    async def update_user_display_name(self, user_uuid: UUID, display_name: str) -> None:
+    async def update_user_display_name(
+        self, user_uuid: UUID, display_name: str
+    ) -> None:
         """Update a user's display name."""
 
     # Role operations
diff --git a/passkey/db/sql.py b/passkey/db/sql.py
index a9bec81..0074b0f 100644
--- a/passkey/db/sql.py
+++ b/passkey/db/sql.py
@@ -271,7 +271,9 @@ class DB(DatabaseInterface):
         async with self.session() as session:
             session.add(UserModel.from_dataclass(user))
 
-    async def update_user_display_name(self, user_uuid: UUID, display_name: str) -> None:
+    async def update_user_display_name(
+        self, user_uuid: UUID, display_name: str
+    ) -> None:
         async with self.session() as session:
             stmt = (
                 update(UserModel)