Dean Glover expects to keep Damien McCrory at Port Vale until January after speaking to Plymouth.
The versatile 18-year-old joined Port Vale on an initial one-month loan deal in October.
He was due to return to Home Park after Saturday's FA Cup clash with Huddersfield but Glover has now made contact with the Pilgrims to discuss his future.
The two clubs have agreed for McCrory to extend his stay with the League Two club and a deal is expected to be finalised in the next couple of days.
"Damien has done well for us and we are more than happy to tie up a deal which will see him at Port Vale until the New Year," manager Glover told the club's official website.
"He will miss our next two games, however, as he has been called up for international duty (with Republic of Ireland Under 19s), but he will still get a few games in for us once he returns to Vale Park.
Plymouth boss Paul Sturrock added: "I always wanted him to stay out on loan for three months anyway and he is proving me totally right."