diff --git a/lib/datasource.js b/lib/datasource.js
index c55ed685..6f3a088c 100644
--- a/lib/datasource.js
+++ b/lib/datasource.js
@@ -392,6 +392,7 @@ DataSource.prototype.defineScopes = function (modelClass, scopes) {
  * @param relations
  */
 DataSource.prototype.defineRelations = function (modelClass, relations) {
+  var self = this;
 
   // Create a function for the closure in the loop
   var createListener = function (name, relation, targetModel, throughModel) {
@@ -428,7 +429,7 @@ DataSource.prototype.defineRelations = function (modelClass, relations) {
 
   // Set up the relations
   if (relations) {
-    for (var rn in relations) {
+    Object.keys(relations).forEach(function(rn) {
       var r = relations[rn];
       assert(DataSource.relationTypes.indexOf(r.type) !== -1, "Invalid relation type: " + r.type);
       var targetModel, polymorphicName;
@@ -447,12 +448,12 @@ DataSource.prototype.defineRelations = function (modelClass, relations) {
       }
       
       if (r.model) {
-        targetModel = isModelClass(r.model) ? r.model : this.getModel(r.model, true);
+        targetModel = isModelClass(r.model) ? r.model : self.getModel(r.model, true);
       }
       
       var throughModel = null;
       if (r.through) {
-        throughModel = isModelClass(r.through) ? r.through : this.getModel(r.through, true);
+        throughModel = isModelClass(r.through) ? r.through : self.getModel(r.through, true);
       }
       
       if ((targetModel && !isModelDataSourceAttached(targetModel)) 
@@ -469,7 +470,7 @@ DataSource.prototype.defineRelations = function (modelClass, relations) {
         }
         modelClass[r.type].call(modelClass, rn, params);
       }
-    }
+    });
   }
 };