Index: stable/4/sys/modules/sound/driver/Makefile.inc
===================================================================
--- stable/4/sys/modules/sound/driver/Makefile.inc	(revision 71950)
+++ stable/4/sys/modules/sound/driver/Makefile.inc	(revision 71951)
@@ -1,3 +1,6 @@
 # $FreeBSD$
 
+SRCS		+= ac97_if.h channel_if.h feeder_if.h mixer_if.h
+SRCS		+= ac97_if.c channel_if.c feeder_if.c mixer_if.c
+
 .include "../Makefile.inc"
Index: stable/4/sys/modules/sound/pcm/Makefile
===================================================================
--- stable/4/sys/modules/sound/pcm/Makefile	(revision 71950)
+++ stable/4/sys/modules/sound/pcm/Makefile	(revision 71951)
@@ -1,10 +1,12 @@
 # $FreeBSD$
 
 .PATH:		${.CURDIR}/../../../dev/sound/pcm
 KMOD		= snd_pcm
 SRCS		= device_if.h bus_if.h isa_if.h pci_if.h
-SRCS		+= ac97.c channel.c dsp.c fake.c
-SRCS		+= feeder.c
+SRCS		+= ac97_if.h channel_if.h feeder_if.h mixer_if.h
+SRCS		+= ac97_if.c channel_if.c feeder_if.c mixer_if.c
+SRCS		+= ac97.c buffer.c channel.c dsp.c fake.c
+SRCS		+= feeder.c feeder_fmt.c
 SRCS		+= mixer.c sound.c
 
 .include <bsd.kmod.mk>