diff --git a/science/py-openbabel/Makefile b/science/py-openbabel/Makefile
index a6353eee68e7..d4fe048259f5 100644
--- a/science/py-openbabel/Makefile
+++ b/science/py-openbabel/Makefile
@@ -1,24 +1,32 @@
 PORTNAME=	openbabel
 DISTVERSION=	3.1.1.1
 CATEGORIES=	science # chemistry
 MASTER_SITES=	PYPI
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	Chemical toolbox designed to speak the many languages of chemical data
 WWW=		https://openbabel.org/wiki/Main_Page
 
 LICENSE=	GPLv2+
 
 BUILD_DEPENDS=	swig:devel/swig
 LIB_DEPENDS=	libopenbabel.so:science/openbabel
 
 USES=		python
 USE_PYTHON=	distutils autoplist
 
 BINARY_ALIAS=	python=${PYTHON_CMD}
 
+.include <bsd.port.options.mk>
+
+post-patch:
+.if ${OPSYS} == FreeBSD && ( ${OSVERSION} >= 1400091 || ( ${OSVERSION} >= 1302507 && ${OSVERSION} < 1400000 ))
+	@${REINPLACE_CMD} -e 's|binary_function|__binary_function|g' \
+		${WRKSRC}/openbabel/openbabel-python.i
+.endif
+
 post-install:
 	@${STRIP_CMD} ${STAGEDIR}${PYTHON_SITELIBDIR}/openbabel/_openbabel${PYTHON_EXT_SUFFIX}.so
 
 .include <bsd.port.mk>