diff --git a/website/src/js/livestream.js b/website/src/js/livestream.js
index 0b170bd9df..71941cffba 100644
--- a/website/src/js/livestream.js
+++ b/website/src/js/livestream.js
@@ -19,6 +19,15 @@ function showLocalTime() {
     local.removeAttribute('hidden');
 }
 
+function setSignupSource() {
+    const field = document.querySelector('input[name="SOURCE"]');
+    if (!field) return;
+
+    const inHash = new URLSearchParams(location.hash.replace(/^#\??/, '')).get('utm_source');
+    const source = inHash ?? new URLSearchParams(location.search).get('utm_source');
+    if (source && /^[\w.-]{1,40}$/.test(source)) field.value = source;
+}
+
 function setupRegisterOverlay() {
     const overlay = document.getElementById('register');
     const openBtn = document.querySelector('.register-btn');
@@ -67,5 +76,6 @@ function trackNavColor() {
 }
 
 showLocalTime();
+setSignupSource();
 setupRegisterOverlay();
 trackNavColor();
diff --git a/website/src/livestream.html b/website/src/livestream.html
index 093fae001b..57dd3c28af 100644
--- a/website/src/livestream.html
+++ b/website/src/livestream.html
@@ -96,6 +96,7 @@ templateEngineOverride: njk
 
             <form action="https://chat.us2.list-manage.com/subscribe/post?u=ddd892b258ae36e5438e6d4e1&amp;id=6f73f92ffa&amp;f_id=006bf8e3f0" method="post" target="_blank">
                 <input type="email" name="EMAIL" placeholder="Enter your email address" aria-label="Email address" required>
+                <input type="hidden" name="SOURCE" value="livestream_page">
                 <span aria-hidden="true" class="bot-field">
                     <input type="text" name="b_ddd892b258ae36e5438e6d4e1_6f73f92ffa" tabindex="-1" value="">
                 </span>