diff --git a/sys/boot/i386/btx/lib/Makefile b/sys/boot/i386/btx/lib/Makefile
index 0eba8f91616..fb56ca1772e 100644
--- a/sys/boot/i386/btx/lib/Makefile
+++ b/sys/boot/i386/btx/lib/Makefile
@@ -1,14 +1,11 @@
 # $FreeBSD$
 
 OBJS=		btxcsu.o btxsys.o btxv86.o
-CLEANFILES+=	crt0.o ${OBJS}
+CLEANFILES=	crt0.o
 
 all: crt0.o
 
 crt0.o: ${OBJS}
 	${LD} ${LDFLAGS} -i -o ${.TARGET} ${OBJS}
 
-.include <bsd.lib.mk>
-
-.s.o:
-	${AS} ${AFLAGS} -o ${.TARGET} ${.IMPSRC}
+.include <bsd.prog.mk>
diff --git a/sys/boot/pc98/btx/lib/Makefile b/sys/boot/pc98/btx/lib/Makefile
index 0eba8f91616..fb56ca1772e 100644
--- a/sys/boot/pc98/btx/lib/Makefile
+++ b/sys/boot/pc98/btx/lib/Makefile
@@ -1,14 +1,11 @@
 # $FreeBSD$
 
 OBJS=		btxcsu.o btxsys.o btxv86.o
-CLEANFILES+=	crt0.o ${OBJS}
+CLEANFILES=	crt0.o
 
 all: crt0.o
 
 crt0.o: ${OBJS}
 	${LD} ${LDFLAGS} -i -o ${.TARGET} ${OBJS}
 
-.include <bsd.lib.mk>
-
-.s.o:
-	${AS} ${AFLAGS} -o ${.TARGET} ${.IMPSRC}
+.include <bsd.prog.mk>