diff --git a/src/activitypub/feps.js b/src/activitypub/feps.js
index 01fc3d46d0..262010b7da 100644
--- a/src/activitypub/feps.js
+++ b/src/activitypub/feps.js
@@ -58,7 +58,7 @@ Feps.announce = async function announce(id, activity) {
 		if (isMain) {
 			activitypub.helpers.log(`[activitypub/inbox.announce(1b12)] Announcing plain object (${activity.id}) to followers of cid ${cid} and ${relays.length} relays`);
 			await activitypub.send('cid', localCid ? cid : 0, targets, {
-				id: `${nconf.get('url')}/post/${encodeURIComponent(id)}#activity/announce/${now}`,
+				id: `${nconf.get('url')}/post/${encodeURIComponent(id)}#activity/announce/${localCid ? `cid/${cid}` : 'uid/0'}`,
 				type: 'Announce',
 				actor: localCid ? `${nconf.get('url')}/category/${cid}` : `${nconf.get('url')}/actor`,
 				to,
@@ -70,7 +70,7 @@ Feps.announce = async function announce(id, activity) {
 
 	activitypub.helpers.log(`[activitypub/inbox.announce(1b12)] Announcing ${activity.type} (${activity.id}) to followers of cid ${cid} and ${relays.length} relays`);
 	await activitypub.send('cid', localCid ? cid : 0, targets, {
-		id: `${nconf.get('url')}/post/${encodeURIComponent(id)}#activity/announce/${now + 1}`,
+		id: `${nconf.get('url')}/post/${encodeURIComponent(id)}#activity/announce/${now}`,
 		type: 'Announce',
 		actor: localCid ? `${nconf.get('url')}/category/${cid}` : `${nconf.get('url')}/actor`,
 		to,
diff --git a/src/activitypub/out.js b/src/activitypub/out.js
index 3ebadcce98..6a267a36bc 100644
--- a/src/activitypub/out.js
+++ b/src/activitypub/out.js
@@ -301,7 +301,7 @@ Out.announce.topic = enabledCheck(async (tid) => {
 	}, { cid, uid: utils.isNumber(uid) ? uid : undefined });
 
 	await activitypub.send('cid', cid, Array.from(targets), {
-		id: `${nconf.get('url')}/post/${encodeURIComponent(pid)}#activity/announce/${Date.now()}`,
+		id: `${nconf.get('url')}/post/${encodeURIComponent(pid)}#activity/announce/cid/${cid}`,
 		type: 'Announce',
 		actor: `${nconf.get('url')}/category/${cid}`,
 		to,
@@ -558,13 +558,13 @@ Out.undo.announce = enabledCheck(async (type, id, tid) => {
 
 	// Just undo the announce.
 	await activitypub.send(type, id, Array.from(targets), {
-		id: `${nconf.get('url')}/post/${encodeURIComponent(pid)}#activity/undo:announce/${Date.now()}`,
+		id: `${nconf.get('url')}/post/${encodeURIComponent(pid)}#activity/undo:announce/${type}/${id}`,
 		type: 'Undo',
 		actor: baseUrl,
 		to,
 		cc,
 		object: {
-			id: `${nconf.get('url')}/post/${encodeURIComponent(pid)}#activity/announce/${Date.now()}`, // wrong timestamp btw
+			id: `${nconf.get('url')}/post/${encodeURIComponent(pid)}#activity/announce/${type}/${id}`,
 			type: 'Announce',
 			actor: baseUrl,
 			to,