diff --git a/scripts/upgrade b/scripts/upgrade
index 6e6d100..45122c9 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -29,7 +29,7 @@ ynh_systemd_action --service_name="$app" --action="stop"
 #=================================================
 ynh_script_progression --message="Ensuring downward compatibility..." --weight=1
 
-if [ -z "${expose_port_53:-}" ] && [ "${expose_port_53:-}" = true ]; then
+if [ -z "${expose_port_53:-}" ] || [ "${expose_port_53:-}" = true ]; then
     expose_port_53="true"
 	ynh_app_setting_set --app="$app" --key=expose_port_53 --value="$expose_port_53"
 elif [ -n "${expose_port_53:-}" ] || [ "${expose_port_53:-}" = false ]; then