diff --git a/x-govuk/components/primary-navigation/_primary-navigation.scss b/x-govuk/components/primary-navigation/_primary-navigation.scss
index b7399a0..554eb6b 100644
--- a/x-govuk/components/primary-navigation/_primary-navigation.scss
+++ b/x-govuk/components/primary-navigation/_primary-navigation.scss
@@ -29,6 +29,7 @@
 
 .x-govuk-primary-navigation__item--current {
   border-bottom: $govuk-border-width-narrow solid $govuk-link-colour;
+  box-shadow: 0 1px 0 0 govuk-shade($govuk-link-colour, 33%);
 
   &:hover {
     border-bottom-color: $govuk-link-hover-colour;