diff --git a/science/thermofun/Makefile b/science/thermofun/Makefile
index 395e3421c7df..f739e9cbfc30 100644
--- a/science/thermofun/Makefile
+++ b/science/thermofun/Makefile
@@ -1,36 +1,39 @@
 PORTNAME=	thermofun
 DISTVERSIONPREFIX=	v
 DISTVERSION=	0.4.0
 CATEGORIES=	science # chemistry
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	Code for calculating thermodynamic properties of materials
 
 LICENSE=	LGPL3
 LICENSE_FILE=	${WRKSRC}/COPYING
 
 BUILD_DEPENDS=	nlohmann-json>0:devel/nlohmann-json \
 		spdlog>0:devel/spdlog
 LIB_DEPENDS=	libChemicalFun.so:science/chemicalfun
 
 USES=		cmake compiler:c++14-lang
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	thermohub
 
 CXXFLAGS+=	-DSPDLOG_FMT_EXTERNAL # see https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258073#c3
 
+TEST_ENV=	${MAKE_ENV} PYTHONPATH=${STAGEDIR}${PYTHONPREFIX_SITELIBDIR}
+TEST_WRKSRC=	${WRKSRC}
+
 OPTIONS_DEFINE=		PYTHON
 OPTIONS_DEFAULT=	PYTHON
 OPTIONS_SUB=		yes
 
 PYTHON_USES=		python
-PYTHON_USE=		PYTHON=pytest
+PYTHON_USE=		PYTHON=pytest # 2 tests fail, see https://github.com/thermohub/thermofun/issues/37
 PYTHON_CMAKE_BOOL=	TFUN_BUILD_PYTHON
 PYTHON_CMAKE_ON=	-DFREEBSD_STAGEDIR=${STAGEDIR}
 PYTHON_BUILD_DEPENDS=	pybind11>0:devel/pybind11
 
 post-install-PYTHON-on:
 	@${STRIP_CMD} ${STAGEDIR}${PYTHON_SITELIBDIR}/thermofun/PyThermoFun${PYTHON_EXT_SUFFIX}.so
 
 .include <bsd.port.mk>