RKC Waalwijk right-back Jordi Altena will join Scottish Premiership leaders Heart of Midlothian on 1 January for an undisclosed fee, with Tynecastle manager Derek McInnes indicating the club had to move quickly to sign the defender.
The former Vitesse Arnhem player, 22, has made more than 50 senior appearances and agreed a deal until the summer of 2029.
He could feature in Saturday’s game at home to Livingston, subject to clearance.
McInnes’ side lead the top flight by three points but second-placed Celtic play their game in hand away to Motherwell on Tuesday evening.
“It quickly became clear that if we wanted to move, then the likelihood is he wouldn’t be there next season,” McInnes said.