diff --git a/lms/djangoapps/course_home_api/outline/views.py b/lms/djangoapps/course_home_api/outline/views.py
index d822d980f90..9f9f0efbc98 100644
--- a/lms/djangoapps/course_home_api/outline/views.py
+++ b/lms/djangoapps/course_home_api/outline/views.py
@@ -609,7 +609,7 @@ def completions_dict(self):
         }
 
     @cached_property
-    def aggregator_block_types(self) -> set[str]:
+    def aggregator_block_types(self):
         """
         Return a set of block types that belong to XBlockCompletionMode.AGGREGATOR.