diff --git a/math/py-pystan/Makefile b/math/py-pystan/Makefile
index 1a9a4384d52f..1078d53cd115 100644
--- a/math/py-pystan/Makefile
+++ b/math/py-pystan/Makefile
@@ -1,30 +1,37 @@
 PORTNAME=	pystan
 PORTVERSION=	2.19.0.0
 PORTREVISION=	1
 CATEGORIES=	math python
 MASTER_SITES=	CHEESESHOP
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 
 MAINTAINER=	gmm@tutanota.com
 COMMENT=	Python interface for Stan
 
 LICENSE=	GPLv3
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 USES=		compiler:c++14-lang python:3.6+ shebangfix
 USE_PYTHON=	autoplist distutils
 
+.include <bsd.port.pre.mk>
+
+.if ${PYTHON_REL} >= 30900
+# See PR 262797 - to be upgraded after the modernization of OCaml ports
+BROKEN=		several build errors
+.endif
+
 BUILD_DEPENDS+=	${PYTHON_PKGNAMEPREFIX}cython>0:lang/cython@${PY_FLAVOR}
 BUILD_DEPENDS+=	${PYTHON_PKGNAMEPREFIX}numpy>0:math/py-numpy@${PY_FLAVOR}
 
 RUN_DEPENDS+=	${PYTHON_PKGNAMEPREFIX}cython>0:lang/cython@${PY_FLAVOR}
 RUN_DEPENDS+=	${PYTHON_PKGNAMEPREFIX}numpy>0:math/py-numpy@${PY_FLAVOR}
 
 SHEBANG_FILES=	${WRKSRC}/pystan/stan/lib/stan_math/lib/upgrade-sundials.sh \
 		${WRKSRC}/pystan/stan/lib/stan_math/hooks/pre-commit \
 		${WRKSRC}/pystan/stan/lib/stan_math/runTests.py \
 
 NO_ARCH=	yes
 NO_ARCH_IGNORE=	_api.so _chains.so _misc.so
 
-.include <bsd.port.mk>
+.include <bsd.port.post.mk>