diff --git a/jam-ui/src/helpers/rest.js b/jam-ui/src/helpers/rest.js
index 64644f531..e3f4b28a1 100644
--- a/jam-ui/src/helpers/rest.js
+++ b/jam-ui/src/helpers/rest.js
@@ -963,7 +963,8 @@ export const openMetronome = options => {
  */
 export const getChatMessages = async ({ channel, sessionId, before }) => {
   const params = new URLSearchParams({ channel });
-  if (sessionId) params.append('session_id', sessionId);
+  // Backend expects 'music_session' not 'session_id'
+  if (sessionId) params.append('music_session', sessionId);
   if (before !== undefined) params.append('before', before);
 
   const baseUrl = process.env.REACT_APP_API_BASE_URL;