diff --git a/net-mgmt/nfdump-devel/Makefile b/net-mgmt/nfdump-devel/Makefile
index f3558406c027..e48aabf5a293 100644
--- a/net-mgmt/nfdump-devel/Makefile
+++ b/net-mgmt/nfdump-devel/Makefile
@@ -21,10 +21,16 @@ PLIST_FILES=	bin/nfcapd bin/nfdump bin/nfprofile bin/nfreplay bin/nfclean.pl
 MAN1=		nfcapd.1 nfdump.1 nfprofile.1 nfreplay.1
 PORTDOCS=	AUTHORS ChangeLog INSTALL README
 
+.include <bsd.port.pre.mk>
+
+.if ${OSVERSION} < 500000
+BROKEN=		"Does not compile on FreeBSD 4.x"
+.endif
+
 .if !defined(NOPORTDOCS)
 post-install:
 	@${MKDIR} ${DOCSDIR}
 	cd ${WRKSRC} && ${INSTALL_DATA} ${PORTDOCS} ${DOCSDIR}
 .endif
 
-.include <bsd.port.mk>
+.include <bsd.port.post.mk>
diff --git a/net-mgmt/nfdump/Makefile b/net-mgmt/nfdump/Makefile
index f3558406c027..e48aabf5a293 100644
--- a/net-mgmt/nfdump/Makefile
+++ b/net-mgmt/nfdump/Makefile
@@ -21,10 +21,16 @@ PLIST_FILES=	bin/nfcapd bin/nfdump bin/nfprofile bin/nfreplay bin/nfclean.pl
 MAN1=		nfcapd.1 nfdump.1 nfprofile.1 nfreplay.1
 PORTDOCS=	AUTHORS ChangeLog INSTALL README
 
+.include <bsd.port.pre.mk>
+
+.if ${OSVERSION} < 500000
+BROKEN=		"Does not compile on FreeBSD 4.x"
+.endif
+
 .if !defined(NOPORTDOCS)
 post-install:
 	@${MKDIR} ${DOCSDIR}
 	cd ${WRKSRC} && ${INSTALL_DATA} ${PORTDOCS} ${DOCSDIR}
 .endif
 
-.include <bsd.port.mk>
+.include <bsd.port.post.mk>
diff --git a/net/p5-Net-Z3950-SimpleServer/Makefile b/net/p5-Net-Z3950-SimpleServer/Makefile
index 52568d7a2596..bd65d1c62306 100644
--- a/net/p5-Net-Z3950-SimpleServer/Makefile
+++ b/net/p5-Net-Z3950-SimpleServer/Makefile
@@ -21,4 +21,10 @@ CONFIGURE_ENV+=	LOCALBASE=${LOCALBASE}
 
 MAN3=		Net::Z3950::GRS1.3 Net::Z3950::SimpleServer.3
 
-.include <bsd.port.mk>
+.include <bsd.port.pre.mk>
+
+.if ${OSVERSION} < 500000
+BROKEN=		"Does not compile on FreeBSD 4.x"
+.endif
+
+.include <bsd.port.post.mk>
diff --git a/www/monkey/Makefile b/www/monkey/Makefile
index 0f7372b56cf7..1728618d192a 100644
--- a/www/monkey/Makefile
+++ b/www/monkey/Makefile
@@ -29,7 +29,13 @@ CONFIGURE_ENV+=	EXTRA_CFLAGS="${CFLAGS}" PTHREAD_LIBS="${PTHREAD_LIBS}"
 CFLAGS+=	${PTHREAD_CFLAGS} -I${LOCALBASE}/include
 LDFLAGS+=	-L${LOCALBASE}/lib
 
+.include <bsd.port.pre.mk>
+
+.if ${OSVERSION} < 500000
+BROKEN=		"Does not compile on FreeBSD 4.x"
+.endif
+
 post-install:
 	@${INSTALL_SCRIPT} ${FILESDIR}/monkey.sh ${PREFIX}/etc/rc.d/monkey.sh.sample
 
-.include <bsd.port.mk>
+.include <bsd.port.post.mk>