Chesterfield have signed experienced midfielder Robbie Weir.
Weir had been on trial a the club during pre-season and proved his fitness after recovering from an anterior cruciate ligament injury.
Caldwell told the club’s official website he was delighted with the signing.
“I’d like to thank the club owner and the board for backing me once again in the transfer market,” he said.
“I jumped at the chance to look at Robbie on trial after coming up against him when he was at Burton and I was at Wigan.
“He was always someone who impressed me with his quality. Since he’s been here, he’s been superb and we’re delighted to have got him.”
Weir, who has been handed the number 28 shirt, will be in contention for a place in Chesterfield’s starting line-up at home to Grimsby Town on Saturday.