diff --git a/ci/test_custom_linters.py b/ci/test_custom_linters.py
index 4911e8fd9..77ff03cb1 100644
--- a/ci/test_custom_linters.py
+++ b/ci/test_custom_linters.py
@@ -103,10 +103,7 @@ def test_tests_collected_once(request: pytest.FixtureRequest) -> None:
     for pattern in ci_patterns:
         tests = _tests_from_pattern(ci_pattern=pattern)
         for test in tests:
-            if test in tests_to_patterns:
-                tests_to_patterns[test].add(pattern)
-            else:
-                tests_to_patterns[test] = {pattern}
+            tests_to_patterns.setdefault(test, set()).add(pattern)
 
     for test_name, patterns in tests_to_patterns.items():
         message = (
diff --git a/pyproject.toml b/pyproject.toml
index 4ef7618a7..63b0eeac3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -374,7 +374,7 @@ run.omit = [
     "src/mock_vws/_flask_server/healthcheck.py",
 ]
 run.parallel = true
-run.source = [ "src/", "tests/" ]
+run.source = [ "ci/", "src/", "tests/" ]
 report.exclude_also = [
     "class .*\\bProtocol\\):",
     "if TYPE_CHECKING:",