diff --git a/src/posts.js b/src/posts.js
index 8f65074914..7d75869a45 100644
--- a/src/posts.js
+++ b/src/posts.js
@@ -527,6 +527,7 @@ var async = require('async'),
 	}
 
 	Posts.getPidIndex = function(pid, uid, callback) {
+		callback = callback || function() {};
 		async.parallel({
 			settings: function(next) {
 				user.getSettings(uid, next);