diff --git a/src/backend/core/services/lobby.py b/src/backend/core/services/lobby.py
index 4c51c67e..e3435199 100644
--- a/src/backend/core/services/lobby.py
+++ b/src/backend/core/services/lobby.py
@@ -212,7 +212,7 @@ class LobbyService:
 
         try:
             utils.notify_participants(
-                room_name=room_id,
+                room_name=str(room_id),
                 notification_data={
                     "type": settings.LOBBY_NOTIFICATION_TYPE,
                 },
diff --git a/src/backend/core/tests/services/test_lobby.py b/src/backend/core/tests/services/test_lobby.py
index 8caf8026..fdb77fd6 100644
--- a/src/backend/core/tests/services/test_lobby.py
+++ b/src/backend/core/tests/services/test_lobby.py
@@ -442,7 +442,7 @@ def test_enter_success(
         timeout=settings.LOBBY_WAITING_TIMEOUT,
     )
     mock_notify.assert_called_once_with(
-        room_name=room.id, notification_data={"type": "participantWaiting"}
+        room_name=str(room.id), notification_data={"type": "participantWaiting"}
     )