diff --git a/src/topics/index.js b/src/topics/index.js
index 99adfc9df2..ff864d19a4 100644
--- a/src/topics/index.js
+++ b/src/topics/index.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var _ = require('lodash');
+const validator = require('validator');
 
 var db = require('../database');
 var posts = require('../posts');
@@ -111,9 +112,10 @@ Topics.getTopicsByTids = async function (tids, options) {
 	result.topics.forEach(function (topic, i) {
 		if (topic) {
 			topic.category = result.categoriesMap[topic.cid];
-			topic.user = result.usersMap[topic.uid];
+			topic.user = topic.uid ? result.usersMap[topic.uid] : { ...result.usersMap[topic.uid] };
 			if (result.tidToGuestHandle[topic.tid]) {
-				topic.user.username = result.tidToGuestHandle[topic.tid];
+				topic.user.username = validator.escape(result.tidToGuestHandle[topic.tid]);
+				topic.user.displayname = topic.user.username;
 			}
 			topic.teaser = result.teasers[i] || null;
 			topic.tags = tags[i];
diff --git a/src/topics/posts.js b/src/topics/posts.js
index ae631be1ae..9ebf29a315 100644
--- a/src/topics/posts.js
+++ b/src/topics/posts.js
@@ -68,6 +68,7 @@ module.exports = function (Topics) {
 				// Username override for guests, if enabled
 				if (meta.config.allowGuestHandles && postObj.uid === 0 && postObj.handle) {
 					postObj.user.username = validator.escape(String(postObj.handle));
+					postObj.user.displayname = postObj.user.username;
 				}
 			}
 		});