diff --git a/packages/frontend-shared/js/config.ts b/packages/frontend-shared/js/config.ts
index b83953c18d..0506c3b70d 100644
--- a/packages/frontend-shared/js/config.ts
+++ b/packages/frontend-shared/js/config.ts
@@ -3,6 +3,8 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+import type { Locale } from '../../../locales/index.js';
+
 const address = new URL(document.querySelector<HTMLMetaElement>('meta[property="instance_url"]')?.content || location.href);
 const siteName = document.querySelector<HTMLMetaElement>('meta[property="og:site_name"]')?.content;
 
@@ -14,12 +16,12 @@ export const wsOrigin = location.origin;
 export const lang = localStorage.getItem('lang') ?? 'en-US';
 export const langs = _LANGS_;
 const preParseLocale = localStorage.getItem('locale');
-export let locale = preParseLocale ? JSON.parse(preParseLocale) : null;
+export let locale: Locale = preParseLocale ? JSON.parse(preParseLocale) : null;
 export const version = _VERSION_;
 export const instanceName = siteName === 'Misskey' || siteName == null ? host : siteName;
 export const ui = localStorage.getItem('ui');
 export const debug = localStorage.getItem('debug') === 'true';
 
-export function updateLocale(newLocale): void {
+export function updateLocale(newLocale: Locale): void {
 	locale = newLocale;
 }
diff --git a/packages/frontend-shared/tsconfig.json b/packages/frontend-shared/tsconfig.json
index 65a21f232f..09a8ff76aa 100644
--- a/packages/frontend-shared/tsconfig.json
+++ b/packages/frontend-shared/tsconfig.json
@@ -16,6 +16,11 @@
 		"experimentalDecorators": true,
 		"noImplicitReturns": true,
 		"esModuleInterop": true,
+		"baseUrl": ".",
+		"paths": {
+			"@/*": ["./*"],
+			"@@/*": ["./*"]
+		},
 		"typeRoots": [
 			"./@types",
 			"./node_modules/@types"
@@ -26,6 +31,7 @@
 		]
 	},
 	"include": [
+		"@types/**/*.ts",
 		"js/**/*"
 	],
 	"exclude": [