diff --git a/demo/file/index.html b/demo/file/index.html
index 49982e34..26086461 100644
--- a/demo/file/index.html
+++ b/demo/file/index.html
@@ -10,7 +10,7 @@
   <script type="module" defer src="./index.js"></script>
 </head>
 <body>
-  <h1>Sample database importer</h1>
+  <h1>Sample database import/export</h1>
   <div>
     <input type="file" id="file-import">
   </div>
diff --git a/demo/file/index.js b/demo/file/index.js
index 93d853c5..30f3e29d 100644
--- a/demo/file/index.js
+++ b/demo/file/index.js
@@ -12,16 +12,18 @@ const DBFILE_MAGIC = 'SQLite format 3\x00';
 navigator.serviceWorker.register('service-worker.js', { type: 'module' });
 (async function() {
   // Enable the export button when the service worker is responding.
+  let delay = 25;
+  const start = performance.now();
   while (true) {
-    let delay = 25;
     const response = await fetch('./export?check=true');
     if (response.ok) {
       // @ts-ignore
       document.getElementById('file-export').disabled = false;
       return;
     }
+    if (performance.now() - start > 60_000) throw new Error('service worker timeout');
     await new Promise(resolve => setTimeout(resolve, delay));
-    delay = Math.min(delay * 2, 5000);
+    delay *= 2;
   }
 })();
 
