diff -ruN /usr/ports/sysutils/syslog-ng/Makefile ./Makefile
--- /usr/ports/sysutils/syslog-ng/Makefile	2013-10-24 16:10:59.000000000 +0200
+++ ./Makefile	2013-10-24 16:12:14.000000000 +0200
@@ -77,7 +77,7 @@
 .endif
 
 .if ${PORT_OPTIONS:MSPOOF}
-BUILD_DEPENDS=		${LIBNET_CONFIG}:${PORTSDIR}/net/libnet
+BUILD_DEPENDS+=		${LIBNET_CONFIG}:${PORTSDIR}/net/libnet
 LIBNET_CONFIG?=		${LOCALBASE}/bin/libnet11-config
 CONFIGURE_ARGS+=	--enable-spoof-source --with-libnet=${LOCALBASE}/bin
 CFLAGS+=		`${LIBNET_CONFIG} --cflags` -I${LOCALBASE}/include