diff --git a/optuna_dashboard/_preference_setting.py b/optuna_dashboard/_preference_setting.py
index 73e9b489..d9d7c1c2 100644
--- a/optuna_dashboard/_preference_setting.py
+++ b/optuna_dashboard/_preference_setting.py
@@ -27,7 +27,7 @@ def _register_preference_feedback_component_type(
         value={
             "type": component_type,
             "artifact_key": artifact_key,
-        }
+        },
     )
 
 
diff --git a/optuna_dashboard/_serializer.py b/optuna_dashboard/_serializer.py
index 98db5ffb..f9aeabec 100644
--- a/optuna_dashboard/_serializer.py
+++ b/optuna_dashboard/_serializer.py
@@ -165,7 +165,8 @@ def serialize_study_detail(
         serialized["form_widgets"] = form_widgets
     if serialized["is_preferential"]:
         serialized["feedback_component_type"] = system_attrs.get(
-            _SYSTEM_ATTR_FEEDBACK_COMPONENT, {})
+            _SYSTEM_ATTR_FEEDBACK_COMPONENT, {}
+        )
     if serialized["is_preferential"]:
         serialized["preference_history"] = serialize_preference_history(system_attrs)
         serialized["preferences"] = get_preferences(system_attrs)