diff --git a/src/lib/es2015.core.d.ts b/src/lib/es2015.core.d.ts
index 032a7afc0ecf9..102ed2149632d 100644
--- a/src/lib/es2015.core.d.ts
+++ b/src/lib/es2015.core.d.ts
@@ -302,7 +302,7 @@ interface ObjectConstructor {
      * Returns the names of the enumerable string 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: {}): string[];
+    keys<T>(o: T): (keyof T)[];
 
     /**
      * Returns true if the values are the same value, false otherwise.