diff --git a/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_multi_select_attribute.py b/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_multi_select_attribute.py
index 68faa59..5805194 100644
--- a/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_multi_select_attribute.py
+++ b/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_multi_select_attribute.py
@@ -10,7 +10,7 @@
 @dataclass
 class _MultiSelectAttribute(_Attribute):
 
-    options: set[str]
+    options: t.Set[str]
 
     @classmethod
     def supports(cls, data_dict: dict):
diff --git a/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_single_select_attribute.py b/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_single_select_attribute.py
index ecf5c2a..7ce4309 100644
--- a/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_single_select_attribute.py
+++ b/raillabel_providerkit/validation/validate_onthology/_onthology_classes/_attributes/_single_select_attribute.py
@@ -10,7 +10,7 @@
 @dataclass
 class _SingleSelectAttribute(_Attribute):
 
-    options: set[str]
+    options: t.Set[str]
 
     @classmethod
     def supports(cls, data_dict: dict):