Partick Thistle have completed the signing of Northern Ireland under-21 captain and defender Mark McChrystal from Derry City. The 22-year-old is due to make his debut in Tuesday's First Division game against local rivals Clyde.
McChrystal began his career at Wolverhampton Wanderers.
He spent three years with Wolves before moving to his hometown club, but he did not feature regularly under outgoing manager Stephen Kenny.