Left-back Joseph Mills has joined Oldham from Burnley on a free transfer.
The 24-year-old, who has signed a two-year deal with an option of a further 12 months, spent the beginning of last season on loan with the Latics.
Mills made 14 appearances during his loan spell, before spending the latter part of the season with Shrewsbury.
Manager Lee Johnson said: "He's got a lot of potential. We'll give him an identity and a bit of love and I feel he can be a really good player for us."