diff --git a/modules/web/src/main/ui/help.scala b/modules/web/src/main/ui/help.scala
index f3eeed66de71c..63a5f545f5b73 100644
--- a/modules/web/src/main/ui/help.scala
+++ b/modules/web/src/main/ui/help.scala
@@ -107,7 +107,8 @@ object help:
               row(kbd("n"), trans.study.nextChapter()),
               row(kbd("p"), trans.study.prevChapter()),
               row(frag((1 to 6).map(kbd(_))), trans.site.toggleGlyphAnnotations()),
-              row(frag(kbd("shift"), (1 to 8).map(kbd(_))), trans.site.togglePositionAnnotations())
+              row(frag(kbd("shift"), (1 to 8).map(kbd(_))), trans.site.togglePositionAnnotations()),
+              row(frag(kbd("ctrl"), kbd("z")), "Undo arrow changes")
             )
           ),
           header(trans.site.mouseTricks()),
diff --git a/ui/analyse/src/ctrl.ts b/ui/analyse/src/ctrl.ts
index aa88e519b2078..db8afb4cc215e 100644
--- a/ui/analyse/src/ctrl.ts
+++ b/ui/analyse/src/ctrl.ts
@@ -330,7 +330,7 @@ export default class AnalyseCtrl {
     this.withCg(cg => {
       cg.set(this.makeCgOpts());
       this.setAutoShapes();
-      if (this.node.shapes) cg.setShapes(this.node.shapes as DrawShape[]);
+      if (this.node.shapes) cg.setShapes(this.node.shapes.slice() as DrawShape[]);
     });
   }
 
@@ -395,7 +395,7 @@ export default class AnalyseCtrl {
     }
 
     this.setAutoShapes();
-    if (this.node.shapes) this.chessground.setShapes(this.node.shapes as DrawShape[]);
+    if (this.node.shapes) this.chessground.setShapes(this.node.shapes.slice() as DrawShape[]);
     this.cgVersion.dom = this.cgVersion.js;
   };
 
diff --git a/ui/analyse/src/keyboard.ts b/ui/analyse/src/keyboard.ts
index 331a57f441d2e..0c232dcb3eea1 100644
--- a/ui/analyse/src/keyboard.ts
+++ b/ui/analyse/src/keyboard.ts
@@ -140,6 +140,8 @@ export const bind = (ctrl: AnalyseCtrl) => {
     // = ∞ ⩲ ⩱ ± ∓ +- -+
     for (let i = 1; i < 9; i++)
       kbd.bind(`shift+${i}`, () => ctrl.study?.glyphForm.toggleGlyph(i === 1 ? 10 : 11 + i));
+
+    kbd.bind('mod+z', ctrl.study.undoShapeChange);
   }
 };
 
diff --git a/ui/analyse/src/study/studyCtrl.ts b/ui/analyse/src/study/studyCtrl.ts
index 8a0721bd7e37c..661e575ddb2cd 100644
--- a/ui/analyse/src/study/studyCtrl.ts
+++ b/ui/analyse/src/study/studyCtrl.ts
@@ -86,6 +86,7 @@ export default class StudyCtrl {
   relayRecProp = prop(false);
   nonRelayRecMapProp = storedMap<boolean>('study.rec', 100, () => true);
   chapterFlipMapProp = storedMap<boolean>('chapter.flip', 400, () => false);
+  arrowHistory: Tree.Shape[][] = [];
   data: StudyData;
   vm: StudyVm;
   notif: NotifCtrl;
@@ -271,6 +272,25 @@ export default class StudyCtrl {
 
   isWriting = (): boolean => this.vm.mode.write && !this.isGamebookPlay();
 
+  private updateShapes = (shapes: Tree.Shape[]) => {
+    this.ctrl.tree.setShapes(shapes, this.ctrl.path);
+    this.makeChange(
+      'shapes',
+      this.addChapterId({
+        path: this.ctrl.path,
+        shapes: shapes,
+      }),
+    );
+  };
+
+  undoShapeChange = () => {
+    if (!this.vm.mode.write) return;
+    const last = this.arrowHistory.pop();
+    if (!last) return;
+    this.updateShapes(last);
+    this.ctrl.withCg(cg => cg.setShapes(last.slice() as DrawShape[]));
+  };
+
   makeChange = (...args: StudySocketSendParams): boolean => {
     if (this.isWriting()) {
       this.send(...args);
@@ -413,14 +433,8 @@ export default class StudyCtrl {
   mutateCgConfig = (config: Required<Pick<CgConfig, 'drawable'>>) => {
     config.drawable.onChange = (shapes: Tree.Shape[]) => {
       if (this.vm.mode.write) {
-        this.ctrl.tree.setShapes(shapes, this.ctrl.path);
-        this.makeChange(
-          'shapes',
-          this.addChapterId({
-            path: this.ctrl.path,
-            shapes,
-          }),
-        );
+        this.arrowHistory.push(this.ctrl.node.shapes?.slice() ?? []);
+        this.updateShapes(shapes);
       }
       this.gamebookPlay?.onShapeChange(shapes);
     };
@@ -543,6 +557,7 @@ export default class StudyCtrl {
     this.isRelayAwayFromLive() && !treePath.contains(this.data.chapter.relayPath!, this.ctrl.path);
 
   setPath = (path: Tree.Path, node: Tree.Node) => {
+    this.arrowHistory = [];
     this.onSetPath(path);
     this.commentForm.onSetPath(this.vm.chapterId, path, node);
   };
diff --git a/ui/lib/src/tree/tree.ts b/ui/lib/src/tree/tree.ts
index 46160a45ad311..f78787dc54b4c 100644
--- a/ui/lib/src/tree/tree.ts
+++ b/ui/lib/src/tree/tree.ts
@@ -218,7 +218,7 @@ export function build(root: Tree.Node): TreeWrapper {
     },
     setShapes(shapes: Tree.Shape[], path: Tree.Path) {
       return updateAt(path, function (node: Tree.Node) {
-        node.shapes = shapes;
+        node.shapes = shapes.slice();
       });
     },
     setCommentAt,