diff --git a/src/index.tsx b/src/index.tsx
index 805847f1..e4d9abd2 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -21,25 +21,30 @@ import './app/i18n';
 document.body.classList.add(configClass, varsClass);
 settings.applyTheme();
 
-// Register Service Worker
-if ('serviceWorker' in navigator) {
-  const swUrl =
-    import.meta.env.MODE === 'production'
-      ? `${trimTrailingSlash(import.meta.env.BASE_URL)}/sw.js`
-      : `/dev-sw.js?dev-sw`;
+const registerServiceWorker = async () => {
+  if ('serviceWorker' in navigator) {
+    const swUrl =
+      import.meta.env.MODE === 'production'
+        ? `${trimTrailingSlash(import.meta.env.BASE_URL)}/sw.js`
+        : `/dev-sw.js?dev-sw`;
 
-  navigator.serviceWorker.register(swUrl);
-  navigator.serviceWorker.addEventListener('message', (event) => {
-    if (event.data?.type === 'token' && event.data?.responseKey) {
-      // Get the token for SW.
-      const token = localStorage.getItem('cinny_access_token') ?? undefined;
-      event.source!.postMessage({
-        responseKey: event.data.responseKey,
-        token,
+    await navigator.serviceWorker.register(swUrl);
+
+    navigator.serviceWorker.ready.then((registration) => {
+      navigator.serviceWorker.addEventListener('message', (event) => {
+        if (event.data?.type === 'token' && event.data?.messageId) {
+          const token = localStorage.getItem('cinny_access_token') ?? undefined;
+          registration.active?.postMessage({
+            messageId: event.data.messageId,
+            token,
+          });
+        }
       });
-    }
-  });
-}
+    });
+  }
+};
+
+window.addEventListener('load', registerServiceWorker);
 
 const mountApp = () => {
   const rootContainer = document.getElementById('root');
diff --git a/src/sw.ts b/src/sw.ts
index 11f7f8b2..60ec9ab4 100644
--- a/src/sw.ts
+++ b/src/sw.ts
@@ -3,16 +3,26 @@
 export type {};
 declare const self: ServiceWorkerGlobalScope;
 
+type Message = { messageId: string };
+type MessageListener = (message: Message) => void;
+const messageListeners = new Map<string, MessageListener>();
+
+self.addEventListener('message', (event) => {
+  const { messageId } = event.data;
+  if (typeof messageId === 'string') {
+    messageListeners.get(messageId)?.(event.data);
+    messageListeners.delete(messageId);
+  }
+});
+
+type TokenMessage = Message & {
+  token?: string;
+};
 async function askForAccessToken(client: Client): Promise<string | undefined> {
   return new Promise((resolve) => {
-    const responseKey = Math.random().toString(36);
-    const listener = (event: ExtendableMessageEvent) => {
-      if (event.data.responseKey !== responseKey) return;
-      resolve(event.data.token);
-      self.removeEventListener('message', listener);
-    };
-    self.addEventListener('message', listener);
-    client.postMessage({ responseKey, type: 'token' });
+    const messageId = Math.random().toString(36);
+    messageListeners.set(messageId, (message: TokenMessage) => resolve(message.token));
+    client.postMessage({ messageId, type: 'token' });
   });
 }