diff --git a/server.js b/server.js
index dcc2874..1d065a6 100644
--- a/server.js
+++ b/server.js
@@ -634,7 +634,8 @@ const server = http.createServer(async (req, res) => {
       const brand = m[1];
       const key = (brand === 'faucetwave' ? 'fw' : 't1') + (String(u.searchParams.get('seg') || '').toLowerCase().startsWith('adv') ? '-adv' : '-earn');
       const cookieTail = `; Path=/; SameSite=Lax; Max-Age=${30 * 24 * 3600}${IS_PROD ? '; Secure' : ''}`;
-      const set = ['iap.sponsor=; Path=/; SameSite=Lax; Max-Age=0' + (IS_PROD ? '; Secure' : ''), 'iap.angle=' + key + cookieTail, 'iap.ref=' + encodeURIComponent('legacy:' + brand) + cookieTail];
+      const src = String(u.searchParams.get('src') || '').toLowerCase().replace(/[^a-z0-9.\-]/g, '').slice(0, 40); // e.g. the old domain's splash page
+      const set = ['iap.sponsor=; Path=/; SameSite=Lax; Max-Age=0' + (IS_PROD ? '; Secure' : ''), 'iap.angle=' + key + cookieTail, 'iap.ref=' + encodeURIComponent('legacy:' + brand + (src ? ':' + src : '')) + cookieTail];
       return serveJoinPage(res, '', key, JOIN_ANGLES[key], set);
     }
     if (p === '/unsubscribe' && req.method === 'GET') {