diff --git a/portal/model/UtcDateTime.py b/portal/model/UtcDateTime.py
index 1216228f60030118f17069806af62b375677d441..fb180926f393853310d8d5db7c4b76df67829389 100644
--- a/portal/model/UtcDateTime.py
+++ b/portal/model/UtcDateTime.py
@@ -36,7 +36,7 @@ class UtcDateTime(types.TypeDecorator):
         return None
 
     def process_result_value(
-        self, value: str | datetime, dialect: Dialect
+        self, value: str | None, dialect: Dialect
     ) -> Optional[datetime]:
         if value is None:
             return None