diff --git a/gitea-to-ics.py b/gitea-to-ics.py
index 414c8e3..a0e4df1 100644
--- a/gitea-to-ics.py
+++ b/gitea-to-ics.py
@@ -58,7 +58,11 @@ class Root:
     @cherrypy.expose
     def todo(self):
         authorization = cherrypy.request.headers.get('Authorization', ':')
+        if not authorization:
+            raise cherrypy.HTTPError(401, 'Unauthorized')
         token = get_token(authorization)
+        if not token:
+            raise cherrypy.HTTPError(401, 'Unauthorized')
         combined = get_combined(token)
         if not combined:
             raise cherrypy.HTTPError(401, 'Unauthorized')