diff --git a/app/helpers/user_notifications_helper.rb b/app/helpers/user_notifications_helper.rb
index 728f4cd9ea7..94141a98fa9 100644
--- a/app/helpers/user_notifications_helper.rb
+++ b/app/helpers/user_notifications_helper.rb
@@ -60,7 +60,7 @@ module UserNotificationsHelper
     else
       # Otherwise, try just the first paragraph.
       para = first_paragraph_from(html)
-      raw Sanitize.clean(para, UserNotificationsHelper.sanitize_options)
+      raw Sanitize.clean(para.to_s, UserNotificationsHelper.sanitize_options)
     end
   end
 end