diff --git a/api/activitypub/sendNote.ts b/api/activitypub/sendNote.ts
index b43de80f4eb5b2d1a2ce02ee737c3be33ef0bbea..0bda6e2c5e0669dce571e7f6452d1c6f86c8098f 100644
--- a/api/activitypub/sendNote.ts
+++ b/api/activitypub/sendNote.ts
@@ -104,7 +104,7 @@ export default async function (req: VercelRequest, res: VercelResponse) {
     }
   }
 
-  sentIds.add(...sendingIds);
+  sentIds.push(...sendingIds);
   configRef.set({
     "sentIds": sentIds,
     "lastEpoch": new Date().getTime()