diff --git a/jupyterhub_announcement/announcement.py b/jupyterhub_announcement/announcement.py
index add135b..4a189a0 100644
--- a/jupyterhub_announcement/announcement.py
+++ b/jupyterhub_announcement/announcement.py
@@ -161,6 +161,7 @@ def initialize(self, argv=None):
                         queue=self.queue,
                         fixed_message=self.fixed_message,
                         loader=loader,
+                        service_prefix=self.service_prefix,
                     ),
                     "view",
                 ),
diff --git a/jupyterhub_announcement/handlers.py b/jupyterhub_announcement/handlers.py
index d1834cf..940269f 100644
--- a/jupyterhub_announcement/handlers.py
+++ b/jupyterhub_announcement/handlers.py
@@ -23,18 +23,20 @@ def log(self):
 class AnnouncementViewHandler(AnnouncementHandler):
     """View announcements page"""
 
-    def initialize(self, queue, fixed_message, loader):
+    def initialize(self, queue, fixed_message, loader, service_prefix):
         super().initialize(queue)
         self.fixed_message = fixed_message
         self.loader = loader
         self.env = Environment(loader=self.loader)
         self.template = self.env.get_template("index.html")
+        self.service_prefix = service_prefix
 
     @web.authenticated
     def get(self):
         user = self.get_current_user()
         prefix = self.hub_auth.hub_prefix
         logout_url = url_path_join(prefix, "logout")
+        update_url = url_path_join(self.service_prefix, "update")
         self.write(
             self.template.render(
                 user=user,
@@ -47,6 +49,7 @@ def get(self):
                 no_spawner_check=True,
                 parsed_scopes=user.get("hub_scopes") or [],
                 xsrf_form_html=self.xsrf_form_html,
+                update_url=update_url,
             )
         )
 
diff --git a/templates/index.html b/templates/index.html
index d23319c..92ea6d3 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -14,7 +14,7 @@
 
   {% if user.admin %}
   <div class="row">
-    <form action="/services/announcement/update" method="post" class="col-md-offset-3 col-md-6">
+    <form action="{{ update_url }}" method="post" class="col-md-offset-3 col-md-6">
       {{ xsrf_form_html() | safe }}
       <div class="form-group">
         <label for="announcement">Announcement</label>