Oxford have further bolstered their squad with the arrivals of midfielders Eddie Hutchinson and Carl Pettefer.
Hutchinson has ended a six-year spell at Griffin Park
Hutchinson, 24, has joined from Brentford, while Pettefer, 25, was recently released by Southend.
New-signing Hutchinson told Oxford's website: "I'm a committed sort of player and I can promise the fans I will give it my all in every game."
Pettefer, meanwhile, was restricted to 12 appearances for the Shrimpers last season because of injury.
Hutchinson had also been targeted by Notts County, Port Vale, Barnsley and Huddersfield, according to County boss Steve Thompson.