Chesterfield have completed the permanent signing of defender Liam Cooper from Hull City for an undisclosed fee.
The 21-year-old has signed a three-and-a-half-year contract with the League Two club after initially joining them on loan in early November.
He has made 11 appearances so far for the Spireites and his performances have clearly impressed boss Paul Cook.
Cooper came through the youth ranks at Hull and made 17 appearances for his hometown club after making his debut as a 16-year-old in a Carling Cup tie against Swansea in 2008.
He has also had previous loan spells with Carlisle and Huddersfield.