Carlisle defender Courtney Meppen-Walter has signed a two-and-a-half-year deal with the League One side.
The 19-year-old agreed a one-month deal with the Cumbrians in November after a successful trial period.
He arrived at Brunton Park last month after serving a jail sentence following a road traffic collision which led to two fatalities.
The former Manchester City trainee made his debut in last week's FA Cup win over Brentford.
Manager Graham Kavanagh told the club website: "We made Courtney what we felt was a very good offer and I'm pleased to say we have been able to sit down and get it all finalised.
"I believe there was interest from one or two other areas but I think he has appreciated the way we have treated him and the chance he has been given."