diff --git a/src/mountainash_settings/profiles/profile.py b/src/mountainash_settings/profiles/profile.py
index 84fcd8d..37fce77 100644
--- a/src/mountainash_settings/profiles/profile.py
+++ b/src/mountainash_settings/profiles/profile.py
@@ -109,7 +109,7 @@ def provider_type(self) -> t.Any:
     def post_init(
         self,
         template_settings_parameters: t.Any = None,
-        reinitialise: bool = False,
+        reinitialise: t.Optional[bool] = False,
     ) -> None:
         """Resolve any ``ParameterSpec.template`` fields.