Goalkeeper Sol Brynn has signed a two-year contract extension with the club.
The 22-year-old's new deal runs up to the end of the 2025/26 season.
It comes after a fine first full season of senior football for Sol, who spent the campaign on loan at Swindon Town.
Sol was voted the club's Player of the Season and he was an ever-present between the posts in the league campaign for the Robins.
He also won Swindon's Player of the Month three times over the year, and picked up a string of Man of the Match accolades.
Sol, a former England U18 international who joined Boro's Academy as a nine-year-old, also experienced senior football at Queen of the South where he made 21 appearances on loan during the latter half of 2021.