diff --git a/jupyterhub/auth.py b/jupyterhub/auth.py
index 33a00bef..98308610 100644
--- a/jupyterhub/auth.py
+++ b/jupyterhub/auth.py
@@ -1101,6 +1101,9 @@ class PAMAuthenticator(LocalAuthenticator):
         else:
             return super().normalize_username(username)
 
+    def get_custom_html(self, base_url):
+        return self.custom_html
+
 
 for _old_name, _new_name, _version in [
     ("check_group_whitelist", "check_group_allowed", "1.2"),
diff --git a/jupyterhub/handlers/login.py b/jupyterhub/handlers/login.py
index 16f26f1a..599c8540 100644
--- a/jupyterhub/handlers/login.py
+++ b/jupyterhub/handlers/login.py
@@ -101,7 +101,7 @@ class LoginHandler(BaseHandler):
                     {'next': self.get_argument('next', '')},
                 ),
         }
-        custom_html = Template(self.authenticator.custom_html).render(**context)
+        custom_html = Template(self.authenticator.get_custom_html(self.hub.base_url)).render(**context)
         return self.render_template(
             'login.html',
             **context,