diff --git a/code/LeftAndMain.php b/code/LeftAndMain.php
index aed8a7112..b180e23f5 100644
--- a/code/LeftAndMain.php
+++ b/code/LeftAndMain.php
@@ -62,6 +62,7 @@
  * This is essentially an abstract class which should be subclassed.
  * See {@link CMSMain} for a good example.
  */
+#[\AllowDynamicProperties]
 class LeftAndMain extends Controller implements PermissionProvider
 {