diff --git a/gitea-to-ics.py b/gitea-to-ics.py
index 3a7dfa5..1a7b4bf 100644
--- a/gitea-to-ics.py
+++ b/gitea-to-ics.py
@@ -49,7 +49,7 @@ def process_combined(combined):
     return cal.to_ical()
 
 def get_token(input_token):
-    token = input_token.lstrip("Basic ")
+    token = input_token.removeprefix("Basic ")
     token = b64decode(token).decode('utf8', 'ignore')
     with cherrypy.HTTPError.handle(ValueError, 401):
         _, token = token.split(":", 2)
@@ -58,6 +58,8 @@ def get_token(input_token):
 class Root:
     @cherrypy.expose
     def todo(self):
+        cherrypy.response.headers['WWW-Authenticate'] = \
+                'Basic realm="ICS access"'
         authorization = cherrypy.request.headers.get('Authorization', ':')
         if not authorization:
             raise cherrypy.HTTPError(401, 'Unauthorized')