diff --git a/packages/core/collections/notes.js b/packages/core/collections/notes.js
index 25336cb2f..447c9100d 100644
--- a/packages/core/collections/notes.js
+++ b/packages/core/collections/notes.js
@@ -137,7 +137,7 @@ export default class Notes extends Collection {
    * @param {"asc"|"desc"} sort
    */
   group(by, sort = "desc") {
-    let notes = this.all;
+    let notes = qclone(this.all);
 
     switch (by) {
       case "abc":