diff --git a/science/py-segyio/Makefile b/science/py-segyio/Makefile
index f6d6a9d5ddec..edccde83f452 100644
--- a/science/py-segyio/Makefile
+++ b/science/py-segyio/Makefile
@@ -1,34 +1,36 @@
 PORTNAME=	segyio
 DISTVERSION=	1.9.7
 CATEGORIES=	science python
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
 
 MAINTAINER=	yuri@FreeBSD.org
 COMMENT=	Python binding for segyio, the seismic data library
 
 LICENSE=	LGPL3+
 
 BUILD_DEPENDS=	cmake:devel/cmake \
 		${PYTHON_PKGNAMEPREFIX}distro>0:sysutils/py-distro@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}pip>0:devel/py-pip@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}pytest-runner>=0:devel/py-pytest-runner@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}scikit-build>0:devel/py-scikit-build@${PY_FLAVOR} \
 		${PYTHON_PKGNAMEPREFIX}setuptools_scm>=0:devel/py-setuptools_scm@${PY_FLAVOR}
 LIB_DEPENDS=	libsegyio.so:science/segyio
 RUN_DEPENDS=	${PYNUMPY}
 
 USES=		compiler:c++11-lang python:3.6+
 USE_PYTHON=	distutils autoplist
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	equinor
 
 WRKSRC_SUBDIR=	python
 
 post-install:
 	@${STRIP_CMD} ${STAGEDIR}${PYTHONPREFIX_SITELIBDIR}/segyio/_segyio*.so
 
 do-test: # tests fail: https://github.com/equinor/segyio/issues/511
-	@cd ${WRKSRC} && ${PYTHON_CMD} ${PYSETUP} test
+	@cd ${WRKSRC} && \
+		${PYTHON_CMD} ${PYSETUP} build_ext --inplace && \
+		${PYTHON_CMD} ${PYSETUP} test
 
 .include <bsd.port.mk>