diff --git a/src/socket.io/topics.js b/src/socket.io/topics.js
index d8e6660d73..d80f12956e 100644
--- a/src/socket.io/topics.js
+++ b/src/socket.io/topics.js
@@ -404,7 +404,7 @@ SocketTopics.follow = function(socket, tid, callback) {
 };
 
 SocketTopics.loadMore = function(socket, data, callback) {
-	if(!data || !data.tid || (parseInt(data.after, 10) < 0))  {
+	if(!data || !data.tid || !utils.isNumber(data.after) || parseInt(data.after, 10) < 0)  {
 		return callback(new Error('[[error:invalid-data]]'));
 	}