Index: head/math/ignition-math/Makefile
===================================================================
--- head/math/ignition-math/Makefile	(revision 486015)
+++ head/math/ignition-math/Makefile	(revision 486016)
@@ -1,35 +1,35 @@
 # $FreeBSD$
 
 PORTNAME=	ignition-math
 DISTVERSION=	6.0.0
 CATEGORIES=	math
 MASTER_SITES=	https://bitbucket.org/${BB_ACCOUNT}/${BB_PROJECT}/get/${BB_COMMIT}.tar.gz?dummy=/
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	General purpose math library for robot applications
 
 LICENSE=	APACHE20
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 BUILD_DEPENDS=	ignition-cmake==2:devel/ignition-cmake
 
-USES=		cmake:outsource eigen:3
+USES=		compiler:c++17-lang cmake:outsource eigen:3
 USE_LDCONFIG=	yes
 
 CMAKE_OFF=	BUILD_TESTING
 
 BB_ACCOUNT=	ignitionrobotics
 BB_PROJECT=	ign-math
 BB_COMMIT=	46f3dd24499c
 
 WRKSRC=		${WRKDIR}/${BB_ACCOUNT}-${BB_PROJECT}-${BB_COMMIT}
 
 PLIST_SUB+=	MATH_IGN_VER=math${DISTVERSION:R:R}
 
 do-test: # one test is known to fail: https://bitbucket.org/ignitionrobotics/ign-math/issues/98
 	@cd ${BUILD_WRKSRC} && \
 		${SETENV} ${CONFIGURE_ENV} ${CMAKE_BIN} ${CMAKE_ARGS} -DBUILD_TESTING=ON ${CMAKE_SOURCE_PATH} && \
 		${SETENV} ${MAKE_ENV} ${MAKE_CMD} ${MAKE_ARGS} ${ALL_TARGET} && \
 		${SETENV} ${MAKE_ENV} ${MAKE_CMD} ${MAKE_ARGS} test
 
 .include <bsd.port.mk>