Index: head/math/py-cypari2/Makefile
===================================================================
--- head/math/py-cypari2/Makefile	(revision 536664)
+++ head/math/py-cypari2/Makefile	(revision 536665)
@@ -1,42 +1,42 @@
 # Created by: thierry@pompo.net
 # $FreeBSD$
 
 PORTNAME=	cypari2
 DISTVERSION=	2.1.1
 CATEGORIES=	math python
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 
 MAINTAINER=	thierry@FreeBSD.org
 COMMENT=	Python interface to the number theory library PARI/GP
 
 LICENSE=	GPLv2
 
 BUILD_DEPENDS=	${PYTHON_PKGNAMEPREFIX}cysignals>0:devel/py-cysignals@${PY_FLAVOR}
 LIB_DEPENDS=	libgmp.so:math/gmp	\
 		libpari.so:math/pari
 RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}cysignals>0:devel/py-cysignals@${PY_FLAVOR}
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	sagemath
 
-USES=		perl5 python:3.6+
+USES=		compiler:c11 perl5 python:3.6+
 USE_PERL5=	build
 USE_PYTHON=	cython distutils
 
 OPTIONS_DEFINE=		DOCS
 DOCS_BUILD_DEPENDS=	${PY_SPHINX}
 DOCS_USES=		gmake
 PORTDOCS=		*
 
 pre-configure-DOCS-on:
 	${REINPLACE_CMD} -e 's|python -m|${PYTHON_CMD} -m|'	\
 		${WRKSRC}/docs/Makefile
 
 do-build-DOCS-on:
 	(cd ${WRKSRC}/docs && ${GMAKE} html)
 
 post-build-DOCS-on:
 	${MKDIR} ${STAGEDIR}${DOCSDIR}
 	${CP} -R ${WRKSRC}/docs/build/html/* ${STAGEDIR}${DOCSDIR}
 
 .include <bsd.port.mk>