diff -ruN net/bittwist.orig/Makefile net/bittwist/Makefile
--- net/bittwist.orig/Makefile	Mon Apr 24 14:05:44 2006
+++ net/bittwist/Makefile	Mon Apr 24 13:37:54 2006
@@ -21,8 +21,15 @@
 
 .include <bsd.port.pre.mk>
 
-.if ${OSVERSION} < 500000
-IGNORE=		does not build under 4.x
+# 5.3 is the first version to have round().
+.if ${OSVERSION} < 503001
+IGNORE=	does not build under 5.2 and older (no round())
+.endif
+
+# 5.3 and up do not have a new enough libpcap but does have round().
+# 6.0 and up have both a new enough libpcap and round().
+.if ${OSVERSION} >= 503001 && ${OSVERSION} < 600100
+BUILD_DEPENDS=	${LOCALBASE}/lib/libpcap.a:${PORTSDIR}/net/libpcap
 .endif
 
 .include <bsd.port.post.mk>
diff -ruN net/bittwist.orig/files/patch-Makefile net/bittwist/files/patch-Makefile
--- net/bittwist.orig/files/patch-Makefile	Thu Jan  1 00:00:00 1970
+++ net/bittwist/files/patch-Makefile	Mon Apr 24 11:43:19 2006
@@ -0,0 +1,16 @@
+--- Makefile.orig	Mon Apr 24 11:41:57 2006
++++ Makefile	Mon Apr 24 11:42:54 2006
+@@ -5,10 +5,11 @@
+ bindir = ${exec_prefix}/bin
+ mandir = ${prefix}/man/man1
+ 
+-CC = gcc
++CC ?= gcc
+ DEBUG = -g
+ #CFLAGS = -O2 -Wall $(DEBUG)
+-CFLAGS = -O2 $(DEBUG)
++CFLAGS ?= -O2
++CFLAGS += ${DEBUG}
+ SRC = src
+ DOC = doc
+