diff --git a/pyproject.toml b/pyproject.toml
index 5de8775713..a48bae660f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -125,6 +125,7 @@ select = [
   "PL",   # pylint
   "Q",    # flake8-quotes
   "SIM",  # flake8-simplify
+  "SLOT", # flake8-slots
   "RET",  # flake8-ret
   "T10",  # flake8-debugger
   "UP",   # pyupgrade
diff --git a/tests/unit_tests/test_yaml_util.py b/tests/unit_tests/test_yaml_util.py
index de70a5307d..d6fb5b81f2 100644
--- a/tests/unit_tests/test_yaml_util.py
+++ b/tests/unit_tests/test_yaml_util.py
@@ -907,7 +907,7 @@ def test_format_path_current_obj_without_location_falls_back_to_key():
     """An ESPHomeDataBase current_obj with no esp_range falls back to the key's location."""
 
     class _NoRange(ESPHomeDataBase, str):
-        pass
+        __slots__ = ()
 
     obj = _NoRange.__new__(_NoRange, "value")
     str.__init__(obj)