diff --git a/usr.bin/awk/Makefile b/usr.bin/awk/Makefile
index 8174db83cc3a..7ec2e575c608 100644
--- a/usr.bin/awk/Makefile
+++ b/usr.bin/awk/Makefile
@@ -6,7 +6,7 @@ AWKSRC=	${.CURDIR}/../../contrib/one-true-awk
 PROG=	awk
 SRCS=	awkgram.y b.c lex.c lib.c main.c parse.c proctab.c run.c tran.c ytab.h
 
-CFLAGS+= -DHAS_ISBLANK -I. -I${AWKSRC}
+CFLAGS+= -DHAS_ISBLANK -I. -I${AWKSRC} -DFOPEN_MAX=64
 
 DPADD=	${LIBM}
 LDADD=	-lm