diff --git a/knockout.es5/knockout.es5-tests.ts b/knockout.es5/knockout.es5-tests.ts
index f35ea44b84..4177d303b0 100644
--- a/knockout.es5/knockout.es5-tests.ts
+++ b/knockout.es5/knockout.es5-tests.ts
@@ -54,6 +54,11 @@ class OrderLine {
     public getSubtotal(): string {
         return "$" + (this.price * this.quantity).toFixed(2);
     }
+
+    public dispose() {
+        // Dispose of all the observables of this object to prevent memory leaks
+        ko.untrack(this);
+    }
 }
 
 class Order {
@@ -83,4 +88,4 @@ anOrder.lines.removeAll();
 
 anOrder.lines.destroy(someOrderLine);
 anOrder.lines.destroyAll([someOrderLine]);
-anOrder.lines.destroyAll();
\ No newline at end of file
+anOrder.lines.destroyAll();
diff --git a/knockout.es5/knockout.es5.d.ts b/knockout.es5/knockout.es5.d.ts
index a62f5d8a81..06309059ef 100644
--- a/knockout.es5/knockout.es5.d.ts
+++ b/knockout.es5/knockout.es5.d.ts
@@ -7,6 +7,7 @@
 
 interface KnockoutStatic {
     track(obj: any, propertyNames?: Array<string>): any;
+    untrack(obj: any, propertyNames?: Array<string>): any;
     defineProperty(obj: any, propertyName: string, evaluator: Function): any;
     defineProperty(obj: any, propertyName: string, options: KnockoutDefinePropertyOptions): any;
     getObservable(obj: any, propertyName: string): KnockoutObservable<any>;
@@ -26,4 +27,4 @@ interface Array<T> {
 	destroy(item: T): void;
 	destroyAll(items: T[]): void;
 	destroyAll(): void;
-}
\ No newline at end of file
+}