diff --git a/src/activitypub/inbox.js b/src/activitypub/inbox.js
index 7ae1a47a9e..92615a305c 100644
--- a/src/activitypub/inbox.js
+++ b/src/activitypub/inbox.js
@@ -173,23 +173,7 @@ inbox.announce = async (req) => {
 	winston.info(`[activitypub/inbox/announce] Parsing id ${pid}`);
 
 	if (!cid) { // Topic events from actors followed by users only
-		// No double-announce allowed
-		const existing = await topics.events.find(tid, {
-			type: 'announce',
-			uid: actor,
-			pid,
-		});
-		if (existing.length) {
-			await topics.events.purge(tid, existing);
-		}
-
-		await topics.events.log(tid, {
-			type: 'announce',
-			uid: actor,
-			href: `/post/${encodeURIComponent(pid)}`,
-			pid,
-			timestamp,
-		});
+		await activitypub.notes.announce.add(pid, actor, timestamp);
 	}
 };
 
@@ -389,17 +373,7 @@ inbox.undo = async (req) => {
 				winston.verbose(`[activitypub/inbox/undo] Attempted to undo announce of ${id} but couldn't find it, so doing nothing.`);
 			}
 
-			const tid = await posts.getPostField(id, 'tid');
-			const existing = await topics.events.find(tid, {
-				type: 'announce',
-				uid: actor,
-				pid: id,
-			});
-
-			if (existing.length) {
-				await topics.events.purge(tid, existing);
-			}
-
+			await activitypub.notes.announce.remove(id, actor);
 			notifications.rescind(`announce:post:${id}:uid:${actor}`);
 			break;
 		}
diff --git a/src/activitypub/notes.js b/src/activitypub/notes.js
index 91f01c0bf6..1001e517a6 100644
--- a/src/activitypub/notes.js
+++ b/src/activitypub/notes.js
@@ -304,3 +304,49 @@ Notes.getCategoryFollowers = async (cid) => {
 
 	return uids;
 };
+
+Notes.announce = {};
+
+Notes.announce.list = async ({ pid, tid }) => {
+	let pids = [];
+	if (pid) {
+		pids = [pid];
+	} else if (tid) {
+		let mainPid;
+		([pids, mainPid] = await Promise.all([
+			db.getSortedSetMembers(`tid:${tid}:posts`),
+			topics.getTopicField(tid, 'mainPid'),
+		]));
+		pids.unshift(mainPid);
+	}
+
+	if (!pids.length) {
+		return [];
+	}
+
+	const keys = pids.map(pid => `pid:${pid}:announces`);
+	let announces = await db.getSortedSetsMembersWithScores(keys);
+	announces = announces.reduce((memo, cur, idx) => {
+		if (cur.length) {
+			const pid = pids[idx];
+			cur.forEach(({ value: actor, score: timestamp }) => {
+				memo.push({ pid, actor, timestamp });
+			});
+		}
+		return memo;
+	}, []);
+
+	return announces;
+};
+
+Notes.announce.add = async (pid, actor, timestamp = Date.now()) => {
+	await db.sortedSetAdd(`pid:${pid}:announces`, timestamp, actor);
+};
+
+Notes.announce.remove = async (pid, actor) => {
+	await db.sortedSetRemove(`pid:${pid}:announces`, actor);
+};
+
+Notes.announce.removeAll = async (pid) => {
+	await db.delete(`pid:${pid}:announces`);
+};
diff --git a/src/topics/events.js b/src/topics/events.js
index e0bbcff21e..ca2ca10edb 100644
--- a/src/topics/events.js
+++ b/src/topics/events.js
@@ -10,6 +10,7 @@ const categories = require('../categories');
 const plugins = require('../plugins');
 const translator = require('../translator');
 const privileges = require('../privileges');
+const activitypub = require('../activitypub');
 const utils = require('../utils');
 const helpers = require('../helpers');
 
@@ -176,6 +177,19 @@ async function modifyEvent({ tid, uid, eventIds, timestamps, events }) {
 		});
 	}
 
+	// Add post announces
+	const announces = await activitypub.notes.announce.list({ tid });
+	announces.forEach(({ actor, pid, timestamp }) => {
+		events.push({
+			type: 'announce',
+			uid: actor,
+			href: `/post/${encodeURIComponent(pid)}`,
+			pid,
+			timestamp,
+		});
+		timestamps.push(timestamp);
+	});
+
 	const [users, fromCategories, userSettings] = await Promise.all([
 		getUserInfo(events.map(event => event.uid).filter(Boolean)),
 		getCategoryInfo(events.map(event => event.fromCid).filter(Boolean)),
diff --git a/src/upgrades/4.0.0/announces_zset.js b/src/upgrades/4.0.0/announces_zset.js
new file mode 100644
index 0000000000..3b235439f8
--- /dev/null
+++ b/src/upgrades/4.0.0/announces_zset.js
@@ -0,0 +1,38 @@
+'use strict';
+
+const db = require('../../database');
+const batch = require('../../batch');
+const topics = require('../../topics');
+
+module.exports = {
+	name: 'Save ActivityPub Announces in their own per-post sorted set',
+	timestamp: Date.UTC(2024, 4, 1),
+	method: async function () {
+		const { progress } = this;
+		const bulkOp = [];
+
+		await batch.processSortedSet('topics:tid', async (tids, next) => {
+			await Promise.all(tids.map(async (tid) => {
+				const announces = await topics.events.find(tid, {
+					type: 'announce',
+				});
+
+				if (announces.length) {
+					await Promise.all(announces.map(async (eid) => {
+						const event = await db.getObject(`topicEvent:${eid}`);
+						if (['uid', 'pid', 'timestamp'].every(prop => event.hasOwnProperty(prop))) {
+							bulkOp.push([`pid:${event.pid}:announces`, event.timestamp, event.uid]);
+						}
+					}));
+
+					console.log('piurging', tid);
+					await topics.events.purge(tid, announces);
+				}
+			}));
+
+			progress.incr(tids.length);
+		}, { progress });
+
+		await db.sortedSetAddBulk(bulkOp);
+	},
+};