Index: head/math/py-symcxx/Makefile
===================================================================
--- head/math/py-symcxx/Makefile	(revision 497968)
+++ head/math/py-symcxx/Makefile	(revision 497969)
@@ -1,27 +1,27 @@
 # $FreeBSD$
 
 PORTNAME=	symcxx
 DISTVERSION=	0.1.9
 PORTREVISION=	2
 CATEGORIES=	math python
 MASTER_SITES=	CHEESESHOP
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	Minimal symbolic manipulation python package written in C++
 
 LICENSE=	BSD2CLAUSE
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 RUN_DEPENDS=	${PYNUMPY}
 
-USES=		fortran python # fortran because otherwise "import numpy" fails with wrong libgcc_s.so message
+USES=		fortran python:-3.6 # fortran because otherwise "import numpy" fails with wrong libgcc_s.so message
 USE_PYTHON=	distutils autoplist
 
 post-patch:
 	@truncate -s 0 ${WRKSRC}/README.rst # workaround for https://github.com/bjodah/symcxx/issues/19
 
 post-install:
 	@${STRIP_CMD} ${STAGEDIR}${PYTHONPREFIX_SITELIBDIR}/symcxx/_symcxx.so
 
 .include <bsd.port.mk>