diff --git a/share/mk/bsd.kmod.mk b/share/mk/bsd.kmod.mk
index 3cafc330dcb..936ffdf6655 100644
--- a/share/mk/bsd.kmod.mk
+++ b/share/mk/bsd.kmod.mk
@@ -52,6 +52,8 @@
 #
 # DESTDIR, DISTDIR are set by other Makefiles (e.g. bsd.own.mk)
 #
+# MFILES	Optionally a list of interfaces used by the module.
+#		This file contains a default list of interfaces.
 #
 # +++ targets +++
 #
@@ -278,10 +280,12 @@ ${_src}:
 .endif
 .endfor
 
-.for _srcsrc in kern/bus_if.m kern/device_if.m dev/iicbus/iicbb_if.m \
+MFILES?= kern/bus_if.m kern/device_if.m dev/iicbus/iicbb_if.m \
     dev/iicbus/iicbus_if.m isa/isa_if.m dev/mii/miibus_if.m \
     dev/pccard/card_if.m dev/pccard/power_if.m pci/pci_if.m \
     dev/ppbus/ppbus_if.m dev/smbus/smbus_if.m dev/usb/usb_if.m
+
+.for _srcsrc in ${MFILES}
 .for _ext in c h
 .for _src in ${SRCS:M${_srcsrc:T:R}.${_ext}}
 CLEANFILES+=	${_src}
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index 3cafc330dcb..936ffdf6655 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -52,6 +52,8 @@
 #
 # DESTDIR, DISTDIR are set by other Makefiles (e.g. bsd.own.mk)
 #
+# MFILES	Optionally a list of interfaces used by the module.
+#		This file contains a default list of interfaces.
 #
 # +++ targets +++
 #
@@ -278,10 +280,12 @@ ${_src}:
 .endif
 .endfor
 
-.for _srcsrc in kern/bus_if.m kern/device_if.m dev/iicbus/iicbb_if.m \
+MFILES?= kern/bus_if.m kern/device_if.m dev/iicbus/iicbb_if.m \
     dev/iicbus/iicbus_if.m isa/isa_if.m dev/mii/miibus_if.m \
     dev/pccard/card_if.m dev/pccard/power_if.m pci/pci_if.m \
     dev/ppbus/ppbus_if.m dev/smbus/smbus_if.m dev/usb/usb_if.m
+
+.for _srcsrc in ${MFILES}
 .for _ext in c h
 .for _src in ${SRCS:M${_srcsrc:T:R}.${_ext}}
 CLEANFILES+=	${_src}