diff --git a/Makefile.am b/Makefile.am
index a183fcce..8a52e084 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -313,15 +313,15 @@ numpy_i       = $(srcdir)/src/numpy.i
 
 if HAVE_HDF5
 python-test: $(TEST_PY)
-	source python/trexio-venv/bin/activate
-	python3 -m pytest -v --all $(TEST_PY)
+	. python/trexio-venv/bin/activate && \
+		python3 -m pytest -v --all $(TEST_PY)
 	$(RM) -r  -- __pycache__
 	$(RM) -f  -- test_file_py.h5 unsafe_test_file_py.h5
 	$(RM) -rf -- test_file_py.dir unsafe_test_file_py.dir
 else
 python-test: $(TEST_PY)
-	source python/trexio-venv/bin/activate
-	python3 -m pytest -v $(TEST_PY)
+	. python/trexio-venv/bin/activate && \
+		python3 -m pytest -v $(TEST_PY)
 	$(RM) -r  -- __pycache__
 	$(RM) -rf -- test_file_py.dir unsafe_test_file_py.dir
 endif