diff --git a/plugins/janus_audiobridge.c b/plugins/janus_audiobridge.c
index 8cd87d7fdc..1376711ef7 100644
--- a/plugins/janus_audiobridge.c
+++ b/plugins/janus_audiobridge.c
@@ -5753,6 +5753,7 @@ static void *janus_audiobridge_handler(void *data) {
 					/* User ID already taken */
 					janus_mutex_unlock(&audiobridge->mutex);
 					janus_refcount_decrease(&audiobridge->ref);
+					janus_mutex_unlock(&rooms_mutex);
 					error_code = JANUS_AUDIOBRIDGE_ERROR_ID_EXISTS;
 					JANUS_LOG(LOG_ERR, "User ID %s already exists\n", user_id_str);
 					g_snprintf(error_cause, 512, "User ID %s already exists", user_id_str);