diff --git a/src/main/frontend/handler/history.cljs b/src/main/frontend/handler/history.cljs
index 8988af5f6b..c20117856a 100644
--- a/src/main/frontend/handler/history.cljs
+++ b/src/main/frontend/handler/history.cljs
@@ -46,6 +46,7 @@
   (let [{:keys [editor-cursor app-state]} (undo-redo/undo)]
     (restore-cursor! editor-cursor)
     (restore-app-state! app-state))
+  ;; ugly timeout: avoid save block from frontend.handler.editor.lifecycle/will-unmount
   (js/setTimeout #(state/set-editor-op! nil) 100))
 
 (defn redo!