diff --git a/setup.cfg b/setup.cfg
index ae23eb4..8ed34d5 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -6,7 +6,7 @@ python-tag = py3
 
 [tool:pytest]
 # More options are set in `setup.py` via environment variable `PYTEST_ADDOPTS`
-addopts = --flake8 --isort --cov --cov-report=term --cov-report=xml -r s
+addopts = --flake8 --isort --typeguard-packages=radicale --cov --cov-report=term --cov-report=xml -r s
 norecursedirs = dist .cache .git build Radicale.egg-info .eggs venv
 
 [tool:isort]
diff --git a/setup.py b/setup.py
old mode 100755
new mode 100644
index 55a61c0..a118cc1
--- a/setup.py
+++ b/setup.py
@@ -52,7 +52,7 @@ WEB_FILES = ["web/internal_data/css/icon.png",
 needs_pytest = {"pytest", "test", "ptr"}.intersection(sys.argv)
 pytest_runner = ["pytest-runner"] if needs_pytest else []
 tests_require = ["pytest-runner", "pytest", "pytest-cov", "pytest-flake8",
-                 "pytest-isort", "waitress"]
+                 "pytest-isort", "typeguard", "waitress"]
 os.environ["PYTEST_ADDOPTS"] = os.environ.get("PYTEST_ADDOPTS", "")
 # Mypy only supports CPython
 if sys.implementation.name == "cpython":