diff --git a/firewall/firewall-add b/firewall/firewall-add
index c4c0d45..aa7c240 100755
--- a/firewall/firewall-add
+++ b/firewall/firewall-add
@@ -151,7 +151,8 @@ if [[ -z "$SOURCE_IP" ]]; then
 	if [[ -z "$SOURCE" ]]; then
 		#SOURCE_IP="0.0.0.0/0";
 		echo "No source IP added";
-	elif [ "$SOURCE" == "SOURCE_IFACE" ]; then
+	elif [ "$(set | grep -w SOURCE_IFACE)" != "" ]; then
+		SOURCE=$SOURCE_IFACE;
 		echo "VPN interface added instead of IP or domain name";
 	else
 		IDX=0
@@ -246,7 +247,7 @@ fi
 
 
 prerouting() {
-	if [ "$SOURCE" == "SOURCE_IFACE" ]; then
+	if [ "$(set |grep -w SOURCE_IFACE)" != "" ]; then 
 		debug "$IPTABLES -I PREROUTING -i $SOURCE_IFACE -p $PROTOCOL --dport $SOURCE_PORT -m comment --comment $COMMENT -j DNAT --to $TARGET_IP:$TARGET_PORT"
 		$IPTABLES -w -I PREROUTING -i $SOURCE_IFACE -p $PROTOCOL --dport $SOURCE_PORT -m comment --comment "$COMMENT" -j DNAT --to $TARGET_IP:$TARGET_PORT