--- iptables-1.4.20.orig/include/linux/netfilter/xt_osf.h	2013-08-06 17:48:43.000000000 +0200
+++ iptables-1.4.20/include/linux/netfilter/xt_osf.h	2013-08-15 17:04:26.116554236 +0200
@@ -21,6 +21,7 @@
 #define _XT_OSF_H
 
 #include <linux/types.h>
+#include <linux/tcp.h>
 
 #define MAXGENRELEN		32