diff --git a/packages/sw/src/scripts/create-notification.ts b/packages/sw/src/scripts/create-notification.ts
index 01b9ab5888..03ce2a60d5 100644
--- a/packages/sw/src/scripts/create-notification.ts
+++ b/packages/sw/src/scripts/create-notification.ts
@@ -1,7 +1,7 @@
 /*
  * Notification manager for SW
  */
-declare var self: ServiceWorkerGlobalScope;
+declare let self: ServiceWorkerGlobalScope;
 
 import { swLang } from "@/scripts/lang";
 import { cli } from "@/scripts/operations";
@@ -45,7 +45,7 @@ async function composeNotification<K extends keyof pushNotificationDataMap>(
 		*/
 		case "notification":
 			switch (data.body.type) {
-				case "follow":
+				case "follow": {
 					// users/showの型定義をswos.apiへ当てはめるのが困難なのでapiFetch.requestを直接使用
 					const account = await getAccountFromId(data.userId);
 					if (!account) return null;
@@ -71,6 +71,7 @@ async function composeNotification<K extends keyof pushNotificationDataMap>(
 								  ],
 						},
 					];
+				}
 
 				case "mention":
 					return [
@@ -157,7 +158,7 @@ async function composeNotification<K extends keyof pushNotificationDataMap>(
 						},
 					];
 
-				case "reaction":
+				case "reaction": {
 					let reaction = data.body.reaction;
 					let badge: string | undefined;
 
@@ -214,6 +215,7 @@ async function composeNotification<K extends keyof pushNotificationDataMap>(
 							],
 						},
 					];
+				}
 
 				case "pollVote":
 					return [
diff --git a/packages/sw/src/scripts/lang.ts b/packages/sw/src/scripts/lang.ts
index da4f315266..31cfb7bd3e 100644
--- a/packages/sw/src/scripts/lang.ts
+++ b/packages/sw/src/scripts/lang.ts
@@ -1,7 +1,7 @@
 /*
  * Language manager for SW
  */
-declare var self: ServiceWorkerGlobalScope;
+declare let self: ServiceWorkerGlobalScope;
 
 import { get, set } from "idb-keyval";
 import { I18n } from "@/scripts/i18n";
@@ -23,7 +23,7 @@ class SwLang {
 	public i18n: Promise<I18n<any>> | null = null;
 
 	public fetchLocale() {
-		return (this.i18n = this._fetch());
+		return this.i18n === this._fetch();
 	}
 
 	private async _fetch() {
diff --git a/packages/sw/src/scripts/notification-read.ts b/packages/sw/src/scripts/notification-read.ts
index 5b2030d989..9ea4528776 100644
--- a/packages/sw/src/scripts/notification-read.ts
+++ b/packages/sw/src/scripts/notification-read.ts
@@ -1,4 +1,4 @@
-declare var self: ServiceWorkerGlobalScope;
+declare let self: ServiceWorkerGlobalScope;
 
 import { get } from "idb-keyval";
 import { pushNotificationDataMap } from "@/types";
diff --git a/packages/sw/src/scripts/operations.ts b/packages/sw/src/scripts/operations.ts
index a192a9bd7e..ae76d6ecff 100644
--- a/packages/sw/src/scripts/operations.ts
+++ b/packages/sw/src/scripts/operations.ts
@@ -2,7 +2,7 @@
  * Operations
  * 各種操作
  */
-declare var self: ServiceWorkerGlobalScope;
+declare let self: ServiceWorkerGlobalScope;
 
 import * as Misskey from "calckey-js";
 import { SwMessage, swMessageOrderType } from "@/types";
diff --git a/packages/sw/src/sw.ts b/packages/sw/src/sw.ts
index 0733400fc3..74603d67ca 100644
--- a/packages/sw/src/sw.ts
+++ b/packages/sw/src/sw.ts
@@ -1,4 +1,4 @@
-declare var self: ServiceWorkerGlobalScope;
+declare let self: ServiceWorkerGlobalScope;
 
 import {
 	createEmptyNotification,