diff --git a/src/utils/YEvent.js b/src/utils/YEvent.js
index dd3cfbf2..76be076b 100644
--- a/src/utils/YEvent.js
+++ b/src/utils/YEvent.js
@@ -78,7 +78,7 @@ export class YEvent {
   }
 
   /**
-   * @return {{added:Set<Item>,deleted:Set<Item>,delta:Array<{insert:Array<any>}|{delete:number}|{retain:number}>}}
+   * @return {{added:Set<Item>,deleted:Set<Item>,keys:Map<string,{action:'add'|'update'|'delete',oldValue:any}>,delta:Array<{insert:Array<any>}|{delete:number}|{retain:number}>}}
    */
   get changes () {
     let changes = this._changes