diff --git a/agaric/templates/block/block--system-menu-block--main.html.twig b/agaric/templates/block/block--system-menu-block--main.html.twig
index 8611c9f..8d1419a 100644
--- a/agaric/templates/block/block--system-menu-block--main.html.twig
+++ b/agaric/templates/block/block--system-menu-block--main.html.twig
@@ -1,2 +1,4 @@
+{% extends "@bulma/block/block--system-menu-block.html.twig" %}
+
 {% set classes = classes ?? []|merge(['navbar-menu']) %}
 {% set attributes = attributes.addClass(classes) %}