diff --git a/src/features/tikz-editor/tikz-editor-modal.ts b/src/features/tikz-editor/tikz-editor-modal.ts
index e55e165..2d11dc9 100644
--- a/src/features/tikz-editor/tikz-editor-modal.ts
+++ b/src/features/tikz-editor/tikz-editor-modal.ts
@@ -530,6 +530,12 @@ export class TikzEditorModal extends Modal implements TikzEditorContext {
       return;
     }
 
+    if ((e.ctrlKey || e.metaKey) && e.key.toLowerCase() === 'z') {
+      e.preventDefault();
+      this.handleUndo();
+      return;
+    }
+
     if ((e.ctrlKey || e.metaKey) && e.key.toLowerCase() === 'c') {
       e.preventDefault();
       const uniqueIds = Array.from(new Set(this.selectedVertices.map(v => v.elementId)));
diff --git a/src/features/tikz-editor/utils/tikz-codec.ts b/src/features/tikz-editor/utils/tikz-codec.ts
index 14ecb15..535d810 100644
--- a/src/features/tikz-editor/utils/tikz-codec.ts
+++ b/src/features/tikz-editor/utils/tikz-codec.ts
@@ -305,10 +305,7 @@ export class TikzCodec {
 
   public generate(elements: EditorElement[], pictureOptions: string): string {
     let output = '';
-    output += `\\begin{tikzpicture}${pictureOptions}\n`;
-
-    const stateObj = { elements, pictureOptions };
-    output += `  % [ObsiTeXState:${JSON.stringify(stateObj)}]\n\n`;
+    output += `\\begin{tikzpicture}${pictureOptions}\n\n`;
 
     elements.forEach(elem => {
       const xVal = this.fromCanvasX(elem.x).toFixed(2);