diff --git a/lib/lib.es5.d.ts b/lib/lib.es5.d.ts
index ac73e23d9f620..14d4746e49959 100644
--- a/lib/lib.es5.d.ts
+++ b/lib/lib.es5.d.ts
@@ -254,6 +254,12 @@ interface ObjectConstructor {
       */
     isExtensible(o: any): boolean;
 
+    /**
+      * Returns the names of the enumerable properties and methods of an object.
+      * @param o Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.
+      */
+    keys<o>(o: {}): (keyof o)[];
+
     /**
       * Returns the names of the enumerable properties and methods of an object.
       * @param o Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.