MacGillivray was a youth with Harrogate Railway Athletic before joining Stalybridge Celtic, but it was with Harrogate Town in Conference North that he gained regular first-team starts.
He won a move to Walsall in 2014 but left to join League One rivals Shrewsbury, having only made 19 appearances in three years.
MacGillivray played 14 times in his one season with the Shrews and moved to Portsmouth on a two-year deal after rejecting the offer of a new contract.
However, his form this season has led to the League One leaders agreeing a contract extension this week until summer 2021 and he has set his sights on winning a Scotland call-up.
“There’s some good goalkeepers in that set-up already, but I’ve got to make sure I keep the best I can and keep performing,” he added.
“And if they ever came knocking then that would be an extra special achievement for myself.”
