diff --git a/nextjs-app/app/layout.tsx b/nextjs-app/app/layout.tsx
index 0ee5b9b..82e7c55 100644
--- a/nextjs-app/app/layout.tsx
+++ b/nextjs-app/app/layout.tsx
@@ -76,9 +76,12 @@ export default function RootLayout({
       <head>
         <link rel="preconnect" href="https://analytics.schoolcompare.co.uk" />
         <link rel="preconnect" href="https://api.postcodes.io" />
+        {/* data-domains: the tracker only fires on the production hostnames,
+            so staging (same image, different host) never pollutes Umami */}
         <Script
           src="https://analytics.schoolcompare.co.uk/script.js"
           data-website-id="d7fb0c95-bb6c-4336-8209-bd10077e50dd"
+          data-domains="schoolcompare.co.uk,www.schoolcompare.co.uk"
           data-performance="true"
           strategy="afterInteractive"
         />
