diff --git a/lib/list.js b/lib/list.js
index 4c4158eb..27c2a534 100644
--- a/lib/list.js
+++ b/lib/list.js
@@ -75,7 +75,7 @@ List.prototype.push = function (obj) {
 List.prototype.toObject = function (onlySchema, removeHidden) {
   var items = [];
   this.forEach(function (item) {
-    if (item.toObject) {
+    if (item && typeof item === 'object' && item.toObject) {
       items.push(item.toObject(onlySchema, removeHidden));
     } else {
       items.push(item);