diff --git a/pylint/plugins/hass_enforce_type_hints.py b/pylint/plugins/hass_enforce_type_hints.py
index f618494d389..29fa1daf47c 100644
--- a/pylint/plugins/hass_enforce_type_hints.py
+++ b/pylint/plugins/hass_enforce_type_hints.py
@@ -1660,6 +1660,7 @@ _INHERITANCE_MATCH: dict[str, list[ClassTypeHintMatch]] = {
                 TypeHintMatch(
                     function_name="source",
                     return_type="str",
+                    mandatory=True,
                 ),
                 TypeHintMatch(
                     function_name="distance",