diff --git a/src/client_container.proto b/src/client_container.proto
index c49390056..839b2c328 100644
--- a/src/client_container.proto
+++ b/src/client_container.proto
@@ -93,6 +93,7 @@ message LoginAck {
     optional string client_id = 2; // a new client_id if none is supplied in Login, or just the original client_id echoed back
     optional string token = 3; // the remember me token.  This is useful if you logged in with username/password (otherwise it's just 'token' echoed back)
     optional int32  heartbeat_interval = 4; // set your heartbeat interval to this value
+    optional string music_session_id = 5; // users session id if present
 }
 
 // route_to: server