diff --git a/mail/libdkim/Makefile b/mail/libdkim/Makefile
index 910ffbc93bd5..d5a3b1998bf4 100644
--- a/mail/libdkim/Makefile
+++ b/mail/libdkim/Makefile
@@ -1,27 +1,27 @@
 PORTNAME=	libdkim
 PORTVERSION=	1.0.21
 CATEGORIES=	mail
 MASTER_SITES=	SF
 
 MAINTAINER=	ports@FreeBSD.org
 COMMENT=	DKIM (DomainKeys Identified Mail) library
 WWW=		https://dkim.org/
 
 LICENSE=	APACHE20
 
 USES=		uidfix zip ssl
-CXXFLAGS+=	-std=gnu++98
+USE_CXXSTD=	gnu++98
 USE_LDCONFIG=	YES
 SHLIB_MAJOR=	1
 PLIST_SUB=	SHLIB_MAJOR="${SHLIB_MAJOR}"
 
 WRKSRC=		${WRKDIR}/${PORTNAME}/src
 
 post-patch:
 	${MV} ${WRKSRC}/Makefile ${WRKSRC}/Makefile.prev
 	@${SED} -e "s=%%SHLIB_MAJOR%%=${SHLIB_MAJOR}=g" \
 		${FILESDIR}/Makefile > ${WRKSRC}/Makefile
 
 .include <bsd.port.mk>
 
 PATCH_ARGS+=	-l