diff --git a/libs/ui/src/lib/layout/AppSidebar.tsx b/libs/ui/src/lib/layout/AppSidebar.tsx
index c1f252ae2..c7f094697 100644
--- a/libs/ui/src/lib/layout/AppSidebar.tsx
+++ b/libs/ui/src/lib/layout/AppSidebar.tsx
@@ -46,9 +46,14 @@ export function AppSidebar({
 }: AppSidebarProps) {
   const { t } = useTranslation();
 
+  // Prefer an exact `to` match so sibling routes sharing a path prefix
+  // (e.g. /vessel-registration and /vessel-registration/transfer) don't
+  // both light up. Prefix matching is the fallback, for sub-pages that
+  // aren't themselves in the nav (e.g. /vessel-registration/apply).
+  const exactMatch = navItems.find((i) => i.to === activePath);
   const activeNavItem = (item: NavItem) =>
     !!item.to &&
-    (activePath === item.to || activePath.startsWith(`${item.to}/`));
+    (exactMatch ? item === exactMatch : activePath.startsWith(`${item.to}/`));
 
   return (
     <>