diff --git a/frontend/app/admin/products/EditProductForm.tsx b/frontend/app/admin/products/EditProductForm.tsx
index bd38d6ce..5c393ef2 100644
--- a/frontend/app/admin/products/EditProductForm.tsx
+++ b/frontend/app/admin/products/EditProductForm.tsx
@@ -71,7 +71,7 @@ export default function EditProductForm({ product, onSaved, onDeleted }: Props)
     for (const node of sorted) {
       const prefix = depth === 0 ? '' : depth === 1 ? '\u00a0\u00a0\u00a0↳ ' : '\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0↳ ';
       result.push({ id: node.id, name: node.name, label: prefix + node.name });
-      result.push(...flattenTree(node.children, depth + 1));
+      if (node.children?.length) result.push(...flattenTree(node.children, depth + 1));
     }
     return result;
   }