diff --git a/plinth/modules/sso/templates/login.html b/plinth/modules/sso/templates/login.html
index 9c8c5ab13..0b9938dc7 100644
--- a/plinth/modules/sso/templates/login.html
+++ b/plinth/modules/sso/templates/login.html
@@ -8,7 +8,7 @@
 
 {% block content %}
 
-  <form class="form" method="post">
+  <form class="form form-login" method="post">
 
     <div class="row">
       {% csrf_token %}
diff --git a/plinth/tests/functional/__init__.py b/plinth/tests/functional/__init__.py
index ad20a0b9c..db024270b 100644
--- a/plinth/tests/functional/__init__.py
+++ b/plinth/tests/functional/__init__.py
@@ -284,7 +284,7 @@ def login_with_account(browser, url, username, password=None):
         if login_button:
             browser.fill('username', username)
             browser.fill('password', password)
-            submit(browser)
+            submit(browser, form_class='form-login')
     else:
         browser.visit(base_url + '/plinth/firstboot/welcome')
         submit(browser, form_class='form-start')  # "Start Setup" button