diff --git a/.drone.yml b/.drone.yml
index 37f0429..96efd7d 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -36,10 +36,10 @@ steps:
     depends_on:
       - build-game
       - build-pwa
-  - name: check
+  - name: type-check
     image: node
     commands:
-      - yarn check
+      - yarn type-check
     depends_on:
       - build-game
       - build-pwa
@@ -53,7 +53,7 @@ steps:
     depends_on:
       - prettier
       - eslint
-      - check
+      - type-check
   - name: deploy (preview)
     image: dockette/vercel
     commands:
@@ -65,4 +65,4 @@ steps:
     depends_on:
       - prettier
       - eslint
-      - check
+      - type-check
diff --git a/package.json b/package.json
index 2f74e74..4555ec6 100644
--- a/package.json
+++ b/package.json
@@ -13,9 +13,9 @@
     "dev:pwa": "yarn build:pwa -w",
     "start": "sirv public --no-clear",
     "preview": "yarn build && yarn start",
-    "check": "yarn check:game && yarn check:pwa",
-    "check:game": "svelte-check --tsconfig ./tsconfig.json",
-    "check:pwa": "svelte-check --tsconfig ./src/pwa/tsconfig.json",
+    "type-check": "yarn type-check:game && yarn type-check:pwa",
+    "type-check:game": "svelte-check --tsconfig ./tsconfig.json",
+    "type-check:pwa": "svelte-check --tsconfig ./src/pwa/tsconfig.json",
     "lint": "yarn lint:prettier && yarn lint:eslint",
     "lint:prettier": "pretty-quick --ignore-path .gitignore --check --plugin-search-dir=. .",
     "lint:prettier:all": "prettier --ignore-path .gitignore --check --plugin-search-dir=. .",
@@ -24,7 +24,7 @@
     "fix:prettier": "pretty-quick --ignore-path .gitignore --write --plugin-search-dir=. .",
     "fix:prettier:all": "prettier --ignore-path .gitignore --write --plugin-search-dir=. .",
     "fix:eslint": "eslint --fix --ignore-path .gitignore ./src/",
-    "test": "yarn lint:prettier:all && yarn lint:eslint --max-warnings=0 && yarn check"
+    "test": "yarn lint:prettier:all && yarn lint:eslint --max-warnings=0 && yarn type-check"
   },
   "devDependencies": {
     "@rollup/plugin-node-resolve": "^13.0.5",
diff --git a/src/pwa/service-worker.ts b/src/pwa/service-worker.ts
index 2703c97..cfc4f6d 100644
--- a/src/pwa/service-worker.ts
+++ b/src/pwa/service-worker.ts
@@ -5,7 +5,7 @@ const STATIC_CACHE_NAME = CACHE_NAME + "-" + CACHE_VERSION;
 const INITIAL_FILES_TO_CACHE = ["/", "/index.html", "/build/bundle.js", "/build/bundle.css", "/favicon.png"];
 const CACHE_DENYLIST = ["/manifest.json", "/service-worker.js", "livereload.js"];
 
-const globalScope = self as WorkerGlobalScope as ServiceWorkerGlobalScope;
+const globalScope = self as unknown /* as WorkerGlobalScope */ as ServiceWorkerGlobalScope;
 
 globalScope.addEventListener("install", (event) => {
   console.debug("[ServiceWorker] Install");
@@ -41,13 +41,12 @@ globalScope.addEventListener("fetch", (event) => {
   const path = new URL(event.request.url).pathname;
   console.debug("[ServiceWorker] Fetch", event.request.url, "==", path);
 
-  function getFromFetch(cache: Cache) {
-    return fetch(event.request).then((response) => {
-      if (!CACHE_DENYLIST.includes(path)) {
-        cache.put(path, response.clone());
-      }
-      return response;
-    });
+  async function getFromFetch(cache: Cache) {
+    const response = await fetch(event.request);
+    if (!CACHE_DENYLIST.includes(path)) {
+      cache.put(path, response.clone());
+    }
+    return response;
   }
 
   async function getFromCache() {
diff --git a/tsconfig.json b/tsconfig.json
index 4e10601..af7da68 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,9 +2,10 @@
   "extends": "@tsconfig/svelte/tsconfig.json",
   "target": "es2021",
   "include": ["src/**/*"],
-  "exclude": ["src/service-worker.ts"],
+  "exclude": ["src/pwa/**"],
   "compilerOptions": {
     "strict": true,
-    "isolatedModules": false
+    "isolatedModules": false,
+    "useDefineForClassFields": true
   }
 }