diff -Naur mailnag-0.5.2.org/Mailnag/daemon/mailchecker.py mailnag-0.5.2/Mailnag/daemon/mailchecker.py
--- mailnag-0.5.2.org/Mailnag/daemon/mailchecker.py	2013-11-03 12:24:43.323803657 +0100
+++ mailnag-0.5.2/Mailnag/daemon/mailchecker.py	2013-11-03 12:25:45.896804596 +0100
@@ -147,7 +147,7 @@
 		for mail in new_mails:
 			n = self._get_notification(mail.sender, mail.subject, "mail-unread")
 			notification_id = str(id(n))
-			n.add_action("mark-as-read", _("Mark as read"), self._notification_action_handler, (mail, notification_id), None)			
+			n.add_action("mark-as-read", _("Mark as read"), self._notification_action_handler, (mail, notification_id))			
 			n.show()
 			self._notifications[notification_id] = n
 
@@ -155,7 +155,7 @@
 	def _get_notification(self, summary, body, icon):
 		n = Notify.Notification.new(summary, body, icon)		
 		n.set_category("email")
-		n.add_action("default", "default", self._notification_action_handler, None, None)
+		n.add_action("default", "default", self._notification_action_handler, None)
 
 		return n