diff --git a/usr.bin/yacc/Makefile b/usr.bin/yacc/Makefile
index 677486fd7320..a5f0d1b78ba2 100644
--- a/usr.bin/yacc/Makefile
+++ b/usr.bin/yacc/Makefile
@@ -1,7 +1,8 @@
 #	@(#)Makefile	5.3 (Berkeley) 5/12/90
 # $FreeBSD$
 
-.PATH: ${.CURDIR}/../../contrib/byacc
+BYACC_SRC=	${.CURDIR}/../../contrib/byacc
+.PATH: ${BYACC_SRC}
 
 PROG=	yacc
 SRCS=	closure.c error.c graph.c lalr.c lr0.c main.c mkpar.c output.c \
@@ -12,7 +13,10 @@ CFLAGS+=	-DMIXEDCASE_FILENAMES=1 \
 		-DHAVE_FCNTL_H=1 \
 		-DHAVE_ATEXIT=1 \
 		-DHAVE_MKSTEMP=1
-		
+
+YYPATCH!=	cat ${BYACC_SRC}/VERSION
+CFLAGS+=	-DYYPATCH=${YYPATCH}
+
 LINKS=	${BINDIR}/yacc ${BINDIR}/byacc
 MLINKS=	yacc.1 byacc.1