diff --git a/app/views/layouts/application.html.erb b/app/views/layouts/application.html.erb
index d1426b0fa8..861d271b63 100644
--- a/app/views/layouts/application.html.erb
+++ b/app/views/layouts/application.html.erb
@@ -22,9 +22,9 @@
- <%= javascript_tag nonce: true do -%>
- document.body.className = ((document.body.className) ? document.body.className + ' js-enabled' : 'js-enabled');
- <% end -%>
+ <%= javascript_tag nonce: true do %>
+ document.body.className += ' js-enabled' + ('noModule' in HTMLScriptElement.prototype ? ' govuk-frontend-supported' : '');
+ <% end %>
<%= govuk_skip_link %>