diff --git a/source/settings/migrations.ts b/source/settings/migrations.ts
index 9b55902..c47b6bc 100644
--- a/source/settings/migrations.ts
+++ b/source/settings/migrations.ts
@@ -37,7 +37,8 @@ export function serializeQueue(queue: Queue.Item[]): Record<string, any> {
 
   for (const item of queue) {
     const key = `qi${item.id}`;
-    serialized[key] = item;
+    serialized[key] = {...item};
+    serialized[key].added = item.added.toISOString();
   }
 
   return serialized;
diff --git a/source/settings/settings.ts b/source/settings/settings.ts
index dd3f983..2f208cf 100644
--- a/source/settings/settings.ts
+++ b/source/settings/settings.ts
@@ -47,9 +47,14 @@ export class Settings {
     };
     this.queue.push(item);
 
-    const sync: Record<string, Queue.Item> = {};
-    sync[`qi${id}`] = item;
-    await browser.storage.sync.set(sync);
+    await browser.storage.sync.set({
+      [`qi${id}`]: {
+        added: item.added.toISOString(),
+        id,
+        text,
+        url,
+      },
+    });
   }
 
   public newQueueItemId(): number {
diff --git a/tests/snapshots/tests/migrations.test.ts.md b/tests/snapshots/tests/migrations.test.ts.md
index 861c8f0..69c9ee7 100644
--- a/tests/snapshots/tests/migrations.test.ts.md
+++ b/tests/snapshots/tests/migrations.test.ts.md
@@ -32,7 +32,7 @@ Generated by [AVA](https://avajs.dev).
 
     {
       qi1: {
-        added: Date 2022-03-02 16:00:00 UTC {},
+        added: '2022-03-02T16:00:00.000Z',
         id: 1,
         text: 'Sample',
         url: 'https://example.org',
diff --git a/tests/snapshots/tests/migrations.test.ts.snap b/tests/snapshots/tests/migrations.test.ts.snap
index 2131bf4..a673a36 100644
Binary files a/tests/snapshots/tests/migrations.test.ts.snap and b/tests/snapshots/tests/migrations.test.ts.snap differ