diff --git a/lib/deserializer-utils.js b/lib/deserializer-utils.js
index 1265fd4..e16f2c7 100644
--- a/lib/deserializer-utils.js
+++ b/lib/deserializer-utils.js
@@ -36,7 +36,7 @@ module.exports = function (jsonapi, data, opts) {
       if (included) {
         // To prevent circular references, check if the record type
         // has already been processed in this thread
-        if (ancestry.indexOf(included.type) > -1) {
+        if (ancestry.find((aIncluded) => aIncluded === included.type+':'+included.id)) {
           return Promise
             .all([extractAttributes(included)])
             .then(function (results) {
@@ -47,7 +47,7 @@ module.exports = function (jsonapi, data, opts) {
         }
 
         return Promise
-          .all([extractAttributes(included), extractRelationships(included, ancestry + ':' + included.type + included.id)])
+          .all([extractAttributes(included), extractRelationships(included, [...ancestry, included.type + ':' + included.id])])
           .then(function (results) {
             var attributes = results[0];
             var relationships = results[1];
@@ -146,7 +146,7 @@ module.exports = function (jsonapi, data, opts) {
 
   this.perform = function () {
     return Promise
-      .all([extractAttributes(data), extractRelationships(data, data.type + data.id)])
+      .all([extractAttributes(data), extractRelationships(data, [data.type + ':' + data.id])])
       .then(function (results) {
         var attributes = results[0];
         var relationships = results[1];