MK Dons have signed defender Warren O'Hora from Brighton & Hove Albion on a permanent deal, with terms undisclosed.
The 21-year-old centre-half spent the first part of the season at the League One club, playing 17 games in all competitions.
O'Hora featured for Brighton's under-23 side but never progressed to the first team following his move from Dublin-based Bohemians in January 2018.
"He's been one of our best players this season," said boss Russell Martin.
"The challenge for him now is to establish himself as a top player at this level."