Tyrone Berry completed a last-minute transfer to Rushden & Diamonds yesterday for a nominal fee.
The 18-year-old winger had been on loan to the League Two side since mid-January, but has now signed a permanent contract with the club that will take him through to the end of next season.
"I am delighted we have been able to sign Tyrone," Diamonds boss Barry Hunter told the official website.
"I'm sure he will continue to develop his playing career successfully here at Nene Park."
The only other transfer activity Palace have been involved in during the January window has seen midfielder Sam Togwell extend his loan period at Port Vale until the end of the season.