Young defender Zac Thompson has signed a one-year professional contract with the club.
The 18-year-old right back joined from Everton earlier this season as a second-year scholar and has made 12 appearances in the under-18s and seven in the reserves.
Since arriving he has impressed the coaching staff, and United manager Simon Grayson said: "Zac's done well. We feel he's got a good future. He's got a good work ethic and he's got plenty of potential.
"He's now got time to develop and we'll be looking to see him pushing to be in and around the first team."
The club have the option of extending the deal by a further year.