diff --git a/backend/app/__init__.py b/backend/app/__init__.py
index b85719d..20d1aeb 100644
--- a/backend/app/__init__.py
+++ b/backend/app/__init__.py
@@ -97,22 +97,27 @@ def create_app(config_class=Config):
     # Well-known URLs for CalDAV/CardDAV auto-discovery (iOS, DAVx5, etc.).
     # 301-Redirect bei PROPFIND ist bei einigen Clients zickig, deshalb
     # delegieren wir intern direkt an die DAV-Handler, statt zu redirecten.
+    from flask import request
     from app.dav.caldav import propfind as dav_propfind, options as dav_options
 
-    @app.route('/.well-known/caldav', methods=['GET', 'HEAD'])
-    @app.route('/.well-known/carddav', methods=['GET', 'HEAD'])
-    def wellknown_redirect():
+    def _wellknown_dav():
+        if request.method == 'PROPFIND':
+            return dav_propfind(subpath='')
+        if request.method == 'OPTIONS':
+            return dav_options()
         return redirect('/dav/', code=301)
 
-    @app.route('/.well-known/caldav', methods=['PROPFIND'])
-    @app.route('/.well-known/carddav', methods=['PROPFIND'])
-    def wellknown_propfind():
-        return dav_propfind(subpath='')
-
-    @app.route('/.well-known/caldav', methods=['OPTIONS'])
-    @app.route('/.well-known/carddav', methods=['OPTIONS'])
-    def wellknown_options():
-        return dav_options()
+    app.add_url_rule(
+        '/.well-known/caldav', view_func=_wellknown_dav,
+        methods=['GET', 'HEAD', 'PROPFIND', 'OPTIONS'],
+        provide_automatic_options=False,
+    )
+    app.add_url_rule(
+        '/.well-known/carddav', view_func=_wellknown_dav,
+        endpoint='_wellknown_carddav',
+        methods=['GET', 'HEAD', 'PROPFIND', 'OPTIONS'],
+        provide_automatic_options=False,
+    )
 
     # iCal export (public, no auth)
     @app.route('/ical/<token>')