diff --git a/src/client/app/boot.js b/src/client/app/boot.js
index 218d57d8e..b15046c22 100644
--- a/src/client/app/boot.js
+++ b/src/client/app/boot.js
@@ -32,13 +32,15 @@
 	//#region Detect app name
 	let app = null;
 
-	if (url.pathname == '/docs' || url.pathname.startsWith('/docs/')) app = 'docs';
-	if (url.pathname == '/dev' || url.pathname.startsWith('/dev/')) app = 'dev';
-	if (url.pathname == '/auth' || url.pathname.startsWith('/auth/')) app = 'auth';
+	if (`${url.pathname}/`.startsWith('/docs/')) app = 'docs';
+	if (`${url.pathname}/`.startsWith('/dev/')) app = 'dev';
+	if (`${url.pathname}/`.startsWith('/auth/')) app = 'auth';
 	//#endregion
 
 	//#region Detect the user language
-	let lang = navigator.language.split('-')[0];
+	let lang = navigator.language;
+
+	if (!LANGS.includes(lang)) lang = lang.split('-')[0];
 
 	// The default language is English
 	if (!LANGS.includes(lang)) lang = 'en';
@@ -104,7 +106,7 @@
 	// グローバルにタイマーIDを代入しておく
 	window.mkBootTimer = window.setTimeout(async () => {
 		// Fetch meta
-		const res = await fetch('/api/meta', {
+		const res = await fetch(API + '/meta', {
 			method: 'POST',
 			cache: 'no-cache'
 		});