Fix 'iptables -p !' bug (segfault when `!' used without argument)
diff --git a/extensions/libipt_mac.c b/extensions/libipt_mac.c
index 1b088a8..5779e8b 100644
--- a/extensions/libipt_mac.c
+++ b/extensions/libipt_mac.c
@@ -72,8 +72,7 @@
 
 	switch (c) {
 	case '1':
-		if (check_inverse(optarg, &invert))
-			optind++;
+		check_inverse(optarg, &invert, &optind, 0);
 		parse_mac(argv[optind-1], macinfo);
 		if (invert)
 			macinfo->invert = 1;