diff --git a/setup.cfg b/setup.cfg
index 9726a0c..25d97c2 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -8,7 +8,7 @@ python-tag = py3
 addopts = --flake8 --isort --cov --cov-report=term --cov-report=xml -r s
 norecursedirs = dist .cache .git build Radicale.egg-info .eggs venv
 
-[isort]
+[tool:isort]
 known_standard_library = posixpath
 known_third_party = gunicorn,passlib,pkg_resources,pytest,pytest_cov,vobject