diff --git a/optuna_dashboard/app.py b/optuna_dashboard/app.py
index fdfe1039..e1af9ca9 100644
--- a/optuna_dashboard/app.py
+++ b/optuna_dashboard/app.py
@@ -9,7 +9,7 @@ from typing import Union, Dict, List, Optional, TypeVar, Callable, Any, cast
 
 from bottle import Bottle, BaseResponse, redirect, request, response, static_file
 from optuna.exceptions import DuplicatedStudyError
-from optuna.storages import BaseStorage, get_storage
+from optuna.storages import BaseStorage
 from optuna.trial import FrozenTrial
 from optuna.study import StudyDirection, StudySummary
 
@@ -84,7 +84,7 @@ def get_trials(
         if (
             trials is not None
             and last_fetched_at is not None
-            and datetime.now() - last_fetched_at < timedelta(ttl_seconds)
+            and datetime.now() - last_fetched_at < timedelta(seconds=ttl_seconds)
         ):
             return trials
     trials = storage.get_all_trials(study_id)
@@ -94,9 +94,8 @@ def get_trials(
     return trials
 
 
-def create_app(storage_or_url: Union[str, BaseStorage]) -> Bottle:
+def create_app(storage: BaseStorage) -> Bottle:
     app = Bottle()
-    storage = get_storage(storage_or_url)
 
     @app.hook("before_request")
     def remove_trailing_slashes_hook() -> None:
diff --git a/optuna_dashboard/cli.py b/optuna_dashboard/cli.py
index 931119a7..40d4ec67 100644
--- a/optuna_dashboard/cli.py
+++ b/optuna_dashboard/cli.py
@@ -2,6 +2,7 @@ import argparse
 import os
 
 from bottle import run
+from optuna.storages import RDBStorage
 
 from .app import create_app
 from .version import __version__
@@ -23,7 +24,8 @@ def main() -> None:
     parser.add_argument("--quiet", "-q", help="quiet", action="store_true")
     args = parser.parse_args()
 
-    app = create_app(args.storage)
+    storage = RDBStorage(args.storage)
+    app = create_app(storage)
     run(app, host=args.host, port=args.port, quiet=args.quiet, reloader=AUTO_RELOAD)