diff --git a/program/js/app.js b/program/js/app.js
index c792bb64b..ece521861 100644
--- a/program/js/app.js
+++ b/program/js/app.js
@@ -6727,7 +6727,7 @@ function rcube_webmail()
   this.set_quota = function(content)
   {
     if (this.gui_objects.quotadisplay && content && content.type == 'text')
-      $(this.gui_objects.quotadisplay).html(content.percent+'%').attr('title', content.title);
+      $(this.gui_objects.quotadisplay).text((content.percent||0) + '%').attr('title', content.title);
 
     this.triggerEvent('setquota', content);
     this.env.quota_content = content;