diff --git a/src/topics/create.js b/src/topics/create.js
index 43001a9bd3..8f347c736a 100644
--- a/src/topics/create.js
+++ b/src/topics/create.js
@@ -89,7 +89,7 @@ module.exports = function (Topics) {
 	Topics.post = async function (data) {
 		data = await plugins.hooks.fire('filter:topic.post', data);
 		const { uid } = data;
-		const remoteUid = !utils.isNumber(uid);
+		const remoteUid = activitypub.helpers.isUri(uid);
 
 		const [categoryExists, canCreate, canTag, isAdmin] = await Promise.all([
 			parseInt(data.cid, 10) > 0 ? categories.exists(data.cid) : true,