FreeBSD 5.4 and IPFilter 4.1.8 kernel compilation error

Hi!

I've tried to build a new kernel on my FreeBSD-box with IPFilter
support. Kernel sources are 5.4-p4 and IPFilter is 4.1.8.
I made everything like described in INSTALL.FreeBSD, but 'make
buildkernel' stops with:

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@ -> /usr/src/sys
machine -> /usr/src/sys/i386/include
awk -f @/tools/makeobjops.awk @/kern/bus_if.m -h
awk -f @/tools/makeobjops.awk @/kern/device_if.m -h
awk -f @/tools/vnode_if.awk @/kern/vnode_if.src -h
rm -f .depend
mkdep -f .depend -a -nostdinc -D_KERNEL -DKLD_MODULE -I- -I. -I@ -
I@/contrib/altq -I@/../include -I/usr/include -I/usr/obj/usr/src/sys/
GENERIC /usr/src/sys/modules/io/../../dev/io/iodev.c /usr/src/sys/
modules/io/../../i386/i386/io.c
===> ip6fw
@ -> /usr/src/sys
machine -> /usr/src/sys/i386/include
rm -f .depend
mkdep -f .depend -a -nostdinc -DIPV6FIREWALL -D_KERNEL -DKLD_MODULE
-I- -I. -I@ -I@/contrib/altq -I@/../include -I/usr/include -I/usr/obj/
usr/src/sys/GENERIC /usr/src/sys/modules/ip6fw/../../netinet6/ip6_fw.c
===> ipfilter
@ -> /usr/src/sys
machine -> /usr/src/sys/i386/include
make: don't know how to make ip_rules.c. Stop
*** Error code 2

Stop in /usr/src/sys/modules.
*** Error code 1

Stop in /usr/obj/usr/src/sys/GENERIC.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.

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After disabling IPv6 support for kernel and using /usr/src/sys/
modules/ipfilter/Makefile.orig instead of Makefile kernel compiled
successfully.
Does IPFilter not work on FreeBSD 5.x with IPv6 or did i something
wrong?

Best regards
Andy