diff --git a/divent/bot.py b/divent/bot.py
index 17b6f49..2376103 100644
--- a/divent/bot.py
+++ b/divent/bot.py
@@ -78,7 +78,9 @@ def token_updater(token: str):
     session["oauth2_token"] = token
 
 
-def make_session(token: Optional[Dict[str, str]], state=Optional[str]) -> OAuth2Session:
+def make_session(
+    token: Optional[Dict[str, str]] = None, state: Optional[str] = None
+) -> OAuth2Session:
     return OAuth2Session(
         client_id=OAUTH2_CLIENT_ID,
         token=token,