Index: biology/py-macs2/Makefile
===================================================================
--- biology/py-macs2/Makefile
+++ biology/py-macs2/Makefile
@@ -13,7 +13,7 @@
 
 BUILD_DEPENDS=	${PYTHON_PKGNAMEPREFIX}numpy>0:math/py-numpy@${PY_FLAVOR}
 
-USES=		python
+USES=		python:2.7
 USE_PYTHON=	autoplist concurrent cython distutils
 
 USE_GITHUB=	yes