diff --git a/api/activitypub/sendNote.ts b/api/activitypub/sendNote.ts
index 0bda6e2c5e0669dce571e7f6452d1c6f86c8098f..cae1f1856ca58a67a54b73d771c78ff2bd9d356d 100644
--- a/api/activitypub/sendNote.ts
+++ b/api/activitypub/sendNote.ts
@@ -104,9 +104,9 @@ export default async function (req: VercelRequest, res: VercelResponse) {
     }
   }
 
-  sentIds.push(...sendingIds);
+  sendingIds.add(...sentIds);
   configRef.set({
-    "sentIds": sentIds,
+    "sentIds": Array.from(sendingIds);,
     "lastEpoch": new Date().getTime()
   });