Goalkeeper Mark Travers has joined the club on loan from Premier League side Bournemouth.
The Republic of Ireland international joins on a deal that will keep him on Teesside until the end of the season.
With Sol Brynn and Seny Dieng facing extended spells on the sidelines, Travers arrives from Bournemouth to add strength and experience to the goalkeeping department.
He has made over 100 appearances for Bournemouth and played in all bar one of their league games during their most recent promotion from the Championship to the Premier League, in 2021/22.
Last season, he made 14 appearances during a loan spell with Stoke and this term he has clocked up five Premier League appearances for the Cherries.