diff --git a/core/admin/mailu/sso/views/languages.py b/core/admin/mailu/sso/views/languages.py
index 66c09b1f..ff65af45 100644
--- a/core/admin/mailu/sso/views/languages.py
+++ b/core/admin/mailu/sso/views/languages.py
@@ -3,5 +3,6 @@ import flask
 
 @sso.route('/language/<language>', methods=['POST'])
 def set_language(language=None):
-    flask.session['language'] = language
+    if language:
+        flask.session['language'] = language
     return flask.Response(status=200)
diff --git a/core/admin/mailu/utils.py b/core/admin/mailu/utils.py
index 755be013..9c56d0be 100644
--- a/core/admin/mailu/utils.py
+++ b/core/admin/mailu/utils.py
@@ -92,6 +92,8 @@ babel = flask_babel.Babel()
 @babel.localeselector
 def get_locale():
     """ selects locale for translation """
+    if not app.config['SESSION_COOKIE_NAME'] in flask.request.cookies:
+        return flask.request.accept_languages.best_match(app.config.translations.keys())
     language = flask.session.get('language')
     if not language in app.config.translations:
         language = flask.request.accept_languages.best_match(app.config.translations.keys())