The 30-year-old, who scored eight goals in 84 appearances for the Pilgrims between 2014 and 2016, has since played for Grimsby Town, Morecambe, Oldham Athletic, Port Vale and Walsall during a successful EFL career.

Subject to final National League and Football Association approval, Mills will be eligible to face Southport on Saturday, having been allocated squad number 23.

Reflecting on Mills' arrival, United manager Paul Cox said: "I am absolutely delighted to have Zak onboard.

"I was already relatively happy with our defensive options, but when Zak became available, it was a no-brainer to bring him in.

"He has quality, experience and versatility in abundance. I am sure he will be a great asset."

Snap up your tickets for Mills' homecoming against Southport (here).