diff --git a/src/ol/object.js b/src/ol/object.js
index 428fc54528..4f6bdd38ba 100644
--- a/src/ol/object.js
+++ b/src/ol/object.js
@@ -50,6 +50,7 @@ ol.ObjectEvent = function(type, key) {
   /**
    * The name of the property whose value is changing.
    * @type {string}
+   * @todo api
    */
   this.key = key;