--- src/VBox/HostDrivers/VBoxNetFlt/Makefile.kmk.orig	2020-07-10 02:57:01.000000000 +1000
+++ src/VBox/HostDrivers/VBoxNetFlt/Makefile.kmk	2020-08-22 02:20:06.719600000 +1000
@@ -459,7 +459,7 @@
 
 endif #ifeq ($(KBUILD_TARGET), win)
 
-else if1of ($(KBUILD_TARGET), solaris freebsd) ## @todo merge this with the mixed case stuff.
+else if1of ($(KBUILD_TARGET), solaris bsdsunix freebsd) ## @todo merge this with the mixed case stuff.
 #
 # vboxnetflt(.ko/.o/) - The lower case driver.
 # Note! On Solaris the name has to be <= 8 chars long.
@@ -480,6 +480,7 @@
   #vboxnetflt_LIBS += \
   #	$(PATH_STAGE_LIB)/RuntimeR0Drv$(VBOX_SUFF_LIB)
   vboxnetflt_SOURCES.solaris = solaris/VBoxNetFlt-solaris.c
+  vboxnetflt_SOURCES.bsdsunix = freebsd/VBoxNetFlt-bsdsunix.c
   vboxnetflt_SOURCES.freebsd = freebsd/VBoxNetFlt-freebsd.c
   vboxnetflt_SOURCES = VBoxNetFlt.c
   solaris/VBoxNetFlt-solaris.c_DEFS = VBOX_SVN_REV=$(VBOX_SVN_REV)
@@ -534,6 +535,41 @@
 
 endif # linux
 
+## @todo Properly generate opt_netgraph.h
+ifeq ($(KBUILD_TARGET),bsdsunix)
+ vboxnetflt_DEPS.bsdsunix += $(PATH_OUT)/opt_netgraph.h
+$(PATH_OUT)/opt_netgraph.h:
+	echo > $(PATH_OUT)/opt_netgraph.h
+
+ #
+ # Install source files for compilation on BSDSUniX.
+ # files_vboxnetflt defines VBOX_VBOXNETFLT_SOURCES.
+ #
+ include $(PATH_SUB_CURRENT)/bsdsunix/files_vboxnetflt
+ INSTALLS += VBoxNetFlt-src
+ VBoxNetFlt-src_INST    = bin/src/vboxnetflt/
+ VBoxNetFlt-src_SOURCES = \
+	$(subst $(DQUOTE),,$(VBOX_VBOXNETFLT_SOURCES)) \
+ 	$(VBoxNetFlt-src_0_OUTDIR)/Makefile
+ VBoxNetFlt-src_CLEAN   = \
+ 	$(VBoxNetFlt-src_0_OUTDIR)/Makefile	\
+
+ $$(VBoxNetFlt-src_0_OUTDIR)/Makefile: \
+		$(PATH_SUB_CURRENT)/bsdsunix/Makefile \
+		$$(if $$(eq $$(VBoxNetFlt/bsdsunix/Makefile_VBOX_HARDENED),$$(VBOX_WITH_HARDENING)),,FORCE) \
+		| $$(dir $$@)
+	$(QUIET)$(RM) -f -- $@
+	$(QUIET)$(CP) -f $< $@
+ ifndef VBOX_WITH_HARDENING
+	$(QUIET)$(SED) -e "s;-DVBOX_WITH_HARDENING;;g" --output $@.tmp $@
+	${QUIET}$(MV) -f $@.tmp $@
+ endif
+ ifndef VBOX_WITH_NETFLT_VIMAGE
+	$(QUIET)$(SED) -e "s;-DVIMAGE;;g" --output $@.tmp $@
+	${QUIET}$(MV) -f $@.tmp $@
+ endif
+endif # bsdsunix
+
 # Gross hack for FreeBSD 7, should figure this out properly
 ## @todo Properly generate opt_netgraph.h
 ifeq ($(KBUILD_TARGET),freebsd)