diff --git a/knockout/knockout.d.ts b/knockout/knockout.d.ts
index 1124780e6c..d5f8310cdd 100644
--- a/knockout/knockout.d.ts
+++ b/knockout/knockout.d.ts
@@ -257,7 +257,7 @@ interface KnockoutUtils {
     arrayFilter(array: any[], predicate: (item) => boolean): any[];
 
     arrayPushAll(array: any[], valuesToPush: any[]): any[];
-    
+
     arrayPushAll(array: KnockoutObservableArray<any>, valuesToPush: any[]): any[];
 
     extend(target, source);
@@ -292,6 +292,8 @@ interface KnockoutUtils {
 
     unwrapObservable<T>(value: KnockoutObservable<T>): T;
 
+    peekObservable<T>(value: KnockoutObservable<T>): T;
+
     toggleDomNodeCssClass(node: any, className: string, shouldHaveClass: boolean): void;
 
     //setTextContent(element: any, textContent: string): void; // NOT PART OF THE MINIFIED API SURFACE (ONLY IN knockout-{version}.debug.js) https://github.com/SteveSanderson/knockout/issues/670