Championship strugglers Charlton have completed the signing of midfielder Matt Spring from Luton for an undisclosed fee.
Spring, who terminated his season-long loan with Sheffield United to join the Addicks, will be available for Saturday's relegation six-pointer against Nottingham Forest.
The 29-year-old has agreed an 18-month deal but is initially on loan to enable him to face Forest.
"We're really pleased to get Matty on a permanent signing," said Addicks boss Phil Parkinson.
"He's a quality footballer and an experienced player.
"I've said that there is a certain category of player we're looking for, ones with Championship experience, and Matty fits the bill."