diff --git a/portal/main.py b/portal/main.py
index bbf1a38cd6f7909f6784ff40425a38445fe33a4f..86220faf1137f83724b8f2c27e9b9706d060bce7 100644
--- a/portal/main.py
+++ b/portal/main.py
@@ -6,7 +6,7 @@ bp = Blueprint("main", __name__)
 
 @bp.get("/", defaults={"_": ""})
 @bp.get("/<path:_>")
-def index(_: object) -> str:
+def index(_: str) -> str:
     """
     Serve the index page at /*, i.e. at any path below / and at / itself.