diff --git a/change_munin_ip.sh b/change_munin_ip.sh
index 3c0e481..bbf1410 100755
--- a/change_munin_ip.sh
+++ b/change_munin_ip.sh
@@ -314,6 +314,14 @@ if [[ -z "${MUNIN_CONF_FILE}" ]]; then
    MUNIN_CONF_FILE="${DEFAULT_MUNIN_CONF_FILE}"
 fi
 
+if [[ -z "${IPT_FIREWALL_MAIN_IPV4_FILE}" ]]; then
+   IPT_FIREWALL_MAIN_IPV4_FILE="${DEFAULT_IPT_FIREWALL_MAIN_IPV4_FILE}"
+fi
+
+if [[ -z "${IPT_FIREWALL_MAIN_IPV6_FILE}" ]]; then
+   IPT_FIREWALL_MAIN_IPV6_FILE="${DEFAULT_IPT_FIREWALL_MAIN_IPV6_FILE}"
+fi
+
 if ${BATCH_MODE} && ( [[ -z "${IPv4_ADDRESS_OLD}" ]] || [[ -z "${IPv4_ADDRESS_NEW}" ]] \
                       || [[ -z "${IPv6_ADDRESS_OLD}" ]] || [[ -z "${IPv6_ADDRESS_NEW}" ]] ) ; then