diff --git a/pytest.ini b/pytest.ini
index 2755dc99..4026b96e 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -3,6 +3,6 @@ DJANGO_SETTINGS_MODULE = recipes.test_settings
 testpaths = cookbook/tests
 python_files = tests.py test_*.py *_tests.py
 # uncomment to run coverage reports
-addopts = -n auto --cov=. --cov-report=html:docs/reports/coverage --cov-report=xml:docs/reports/coverage/coverage.xml --junitxml=docs/reports/tests/pytest.xml --html=docs/reports/tests/tests.html
+addopts = -n @NIX_BUILD_CORES@ --cov=. --cov-report=html:docs/reports/coverage --cov-report=xml:docs/reports/coverage/coverage.xml --junitxml=docs/reports/tests/pytest.xml --html=docs/reports/tests/tests.html
 # addopts = -n auto --junitxml=docs/reports/tests/pytest.xml --html=docs/reports/tests/tests.html