diff --git a/ct/openthread-br.sh b/ct/openthread-br.sh
index 273e3fb0..643d1576 100644
--- a/ct/openthread-br.sh
+++ b/ct/openthread-br.sh
@@ -14,6 +14,7 @@ var_disk="${var_disk:-4}"
 var_os="${var_os:-debian}"
 var_version="${var_version:-13}"
 var_unprivileged="${var_unprivileged:-0}"
+var_tun="${var_tun:-yes}"
 
 header_info "$APP"
 variables