diff --git a/src/lib/es5.d.ts b/src/lib/es5.d.ts
index 4112f5a2ae7d7..66410829983fc 100644
--- a/src/lib/es5.d.ts
+++ b/src/lib/es5.d.ts
@@ -238,7 +238,7 @@ interface ObjectConstructor {
       * 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: {}): string[];
+    keys<T>(o: T): (keyof T)[];
 }
 
 /**