The goalkeeper, 20, who was tied to the club until the summer of 2014, has penned an extended deal that will keep him at Brunton Park until 2015.
Boss Greg Abbott told the club's official website: "Mark keeps improving and that is good news for all of us.
"We have seen already this season that he is ready to do a job and we think he is just going to get better and better.
"This gives him a chance to really focus now and to push himself on even further."
The Newcastle-born keeper has made 13 appearances for the Cumbrians this term.
- Sports & Recreation