--- emulators/virtualbox-ose/files/patch-src_VBox_Additions_freebsd_mount__vboxvfs_Makefile.kmk	(revision 486103)
+++ emulators/virtualbox-ose/files/patch-src_VBox_Additions_freebsd_mount__vboxvfs_Makefile.kmk	(working copy)
@@ -13,7 +13,7 @@ 
 +$(error "The FreeBSD guest additions can only be built on FreeBSD!")
 +endif
 +
-+FREEBSD_SRC=	/usr/src
++FREEBSD_SRC?=	/usr/src
 +MOUNT=		${FREEBSD_SRC}/sbin/mount
 +
 +CFLAGS+=-I${MOUNT}
--- emulators/virtualbox-ose-additions/Makefile	(revision 486103)
+++ emulators/virtualbox-ose-additions/Makefile	(working copy)
@@ -76,7 +76,7 @@ 
 BUILD_WRKSRC=	${VBOX_BIN}/src
 
 KMK_BUILDTYPE=	release
-KMK_CONFIG=	VBOX_LIBPATH_X11=${LOCALBASE}
+KMK_CONFIG=	VBOX_LIBPATH_X11=${LOCALBASE} VBOX_FREEBSD_SRC=${SRC_BASE}/sys FREEBSD_SRC=${SRC_BASE}
 KMK_FLAGS=
 
 .if ${PORT_OPTIONS:MDEBUG}