diff --git a/optuna_dashboard/app.py b/optuna_dashboard/app.py
index 5dd95129..947f1099 100644
--- a/optuna_dashboard/app.py
+++ b/optuna_dashboard/app.py
@@ -15,7 +15,7 @@ from optuna.study import StudyDirection, StudySummary
 
 from . import serializer
 
-F = TypeVar('F', bound=Callable[..., Any])
+F = TypeVar("F", bound=Callable[..., Any])
 
 logger = logging.getLogger(__name__)
 
diff --git a/optuna_dashboard/serializer.py b/optuna_dashboard/serializer.py
index a43a1486..6646cfb4 100644
--- a/optuna_dashboard/serializer.py
+++ b/optuna_dashboard/serializer.py
@@ -5,18 +5,27 @@ from optuna.study import StudySummary
 from optuna.trial import FrozenTrial
 
 
-Attribute = TypedDict("Attribute", {
-    "key": str,
-    "value": str,
-})
-IntermediateValue = TypedDict("IntermediateValue", {
-    "step": int,
-    "value": float,
-})
-TrialParam = TypedDict("TrialParam", {
-    "name": str,
-    "value": str,
-})
+Attribute = TypedDict(
+    "Attribute",
+    {
+        "key": str,
+        "value": str,
+    },
+)
+IntermediateValue = TypedDict(
+    "IntermediateValue",
+    {
+        "step": int,
+        "value": float,
+    },
+)
+TrialParam = TypedDict(
+    "TrialParam",
+    {
+        "name": str,
+        "value": str,
+    },
+)
 
 
 def serialize_attrs(attrs: Dict[str, Any]) -> List[Attribute]: