diff --git a/src/keycloak/keycloak_admin.py b/src/keycloak/keycloak_admin.py
index 58d8c65..544a6b6 100644
--- a/src/keycloak/keycloak_admin.py
+++ b/src/keycloak/keycloak_admin.py
@@ -29,7 +29,7 @@
 import copy
 import json
 from builtins import isinstance
-from typing import Optional, Union
+from typing import Optional
 
 import deprecation
 from requests_toolbelt import MultipartEncoder
@@ -84,7 +84,7 @@ class KeycloakAdmin:
     PAGE_SIZE = 100
 
     _auto_refresh_token = None
-    _connection: Union[KeycloakOpenIDConnection, None] = None
+    _connection: Optional[KeycloakOpenIDConnection] = None
 
     def __init__(
         self,