diff --git a/knockout/knockout-2.2.d.ts b/knockout/knockout-2.2.d.ts
index 5d9253e445..fc3137a7db 100644
--- a/knockout/knockout-2.2.d.ts
+++ b/knockout/knockout-2.2.d.ts
@@ -36,6 +36,8 @@ interface KnockoutObservableArrayFunctions extends KnockoutObservableFunctions {
     sort(compareFunction): void;
 
     // Ko specific
+    replace(oldItem: any, newItem: any): void;
+
     remove(item): any[];
     removeAll(items: any[]): any[];
     removeAll(): any[];