Adam Eckersley has become Lee Sinnott's first permanent signing as Port Vale boss after securing a move from Manchester United.
The 22-year-old defender, who primarily plays at left-back but can also operate on the right, joined Port Vale on loan in October.
He made just two appearances during his stay as he was sent off on his debut against Brighton and then suffered an injury that cut his spell short.
But he has now agreed a long-term switch to Port Vale and is relishing the challenge of trying to keep the club in League One.
"They told me before my injury they would like to renew my loan, and obviously with the injury I couldn't come back for six weeks," Eckersley told Port Vale's official website.
"But I believe we have got a good chance of staying up in League One and I am happy to be back, it is a good club with good people here."
He added: "It's a big help knowing most of the players from when I was here before and I also knew one or two them from when I played here in pre-season."