diff --git a/lib/resolver.js b/lib/resolver.js
index deb688680..7095a907f 100644
--- a/lib/resolver.js
+++ b/lib/resolver.js
@@ -540,7 +540,7 @@ Resolver.prototype.resolveTo = function (root, property, resolutionTable, locati
   var sp, i;
   var ref = property.$ref;
   var lroot = root;
-  if (typeof ref !== 'undefined') {
+  if ((typeof ref !== 'undefined') && (ref !== null)) {
     if(ref.indexOf('#') >= 0) {
       var parts = ref.split('#');