diff --git a/src/ol/observable.js b/src/ol/observable.js
index ffb1b4f76f..d856e3c9b3 100644
--- a/src/ol/observable.js
+++ b/src/ol/observable.js
@@ -47,6 +47,7 @@ ol.Observable.prototype.dispatchChangeEvent = function() {
 
 /**
  * @return {number} Revision.
+ * @todo api
  */
 ol.Observable.prototype.getRevision = function() {
   return this.revision_;