Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -16,7 +16,9 @@ LDADD+= -lcurses
 MANDIR=${LOCALBASE}/man/cat
 BINDIR=${LOCALBASE}/sbin
 
-.y.c:
-	${YACC.y} -d -b ${.TARGET:R} -o ${.TARGET} ${.IMPSRC}
+sf-grammer.c sf-grammer.h: sf-grammer.y
+	${YACC.y} -d -b ${.TARGET:R} -o sf-grammer.c sf-grammer.y
+
+sf-scanner.o: sf-grammer.h
 
 .include <bsd.prog.mk>