diff --git a/src/cryptography/x509/extensions.py b/src/cryptography/x509/extensions.py
index f6b130cd884b..f4e830a762dc 100644
--- a/src/cryptography/x509/extensions.py
+++ b/src/cryptography/x509/extensions.py
@@ -2311,7 +2311,7 @@ def __eq__(self, other: object) -> bool:
 
     def __hash__(self) -> int:
         if self.profession_oids is None:
-            profession_oids = (None,)
+            profession_oids: tuple[ObjectIdentifier | None, ...] = (None,)
         else:
             profession_oids = tuple(self.profession_oids)
         return hash(