diff --git a/data/observable/observable.ts b/data/observable/observable.ts
index 565fc58e7..1dff4db84 100644
--- a/data/observable/observable.ts
+++ b/data/observable/observable.ts
@@ -15,16 +15,15 @@ export class Observable implements definition.Observable {
     constructor(json?: any) {
         if (json) {
             this._map = new Map<string, Object>();
-            var that = this;
 
             var definePropertyFunc = function definePropertyFunc(propertyName) {
                 Object.defineProperty(Observable.prototype, propertyName, {
                     get: function () {
-                        return that._map.get(propertyName);
+                        return this._map.get(propertyName);
                     },
                     set: function (value) {
-                        that._map.set(propertyName, value);
-                        that.notify(that._createPropertyChangeData(propertyName, value));
+                        this._map.set(propertyName, value);
+                        this.notify(this._createPropertyChangeData(propertyName, value));
                     },
                     enumerable: true,
                     configurable: true