diff -ru -x '*.Po' -x '*.Plo' cooledit-3.17.17.orig/rxvt/_rxvtlib.h cooledit-3.17.17/rxvt/_rxvtlib.h
--- cooledit-3.17.17.orig/rxvt/_rxvtlib.h	2008-04-17 12:09:05 +0200
+++ cooledit-3.17.17/rxvt/_rxvtlib.h	2008-04-17 12:09:31 +0200
@@ -169,7 +169,9 @@
 #endif
 #include <netinet/in.h>
 #include <arpa/inet.h>
+#ifndef __INTERIX
 #include <net/if.h>
+#endif
 #if !defined(__NetBSD__) && !defined(__OpenBSD__) && !defined(__INTERIX)
 #include <net/if_arp.h>
 #endif