diff --git a/openwrt/package/iptables/files/firewall.init b/openwrt/package/iptables/files/firewall.init
index a7cde95b5f..ad014cbaa3 100755
--- a/openwrt/package/iptables/files/firewall.init
+++ b/openwrt/package/iptables/files/firewall.init
@@ -34,7 +34,7 @@ iptables -t nat -N postrouting_rule
   iptables -A INPUT -j input_rule
 
   # allow
-  iptables -A INPUT ${WAN:+-i \! $WAN} -j ACCEPT	# allow from all interfaces except for wan
+  iptables -A INPUT ${WAN:+\! -i $WAN} -j ACCEPT	# allow from all interfaces except for wan
   iptables -A INPUT -p icmp	-j ACCEPT	# allow ICMP
   iptables -A INPUT -p gre	-j ACCEPT	# allow GRE