diff --git a/portal/api/rest.py b/portal/api/rest.py
index 6474513c5db61d0445b710579fbc2d0f02314b47..e4d89e9d52ea71a717c688288785694bcddd450a 100644
--- a/portal/api/rest.py
+++ b/portal/api/rest.py
@@ -5,7 +5,7 @@ from .blueprint import bp
 
 
 @bp.get("/<path:_>")
-def fallback_not_found(_: object) -> ProblemResponse:
+def fallback_not_found(_: str) -> ProblemResponse:
     """
     If you can't find a matching API endpoint, fallback to returning a 404.