 Mackin drew praise from manager Denis Smith after scoring against Hereford United in a pre-season friendly in July 2005, saying "We wouldn't keep persevering with him if we didn't think he was any good".His first appearance of 2005–06 came as a 90th-minute substitute in a 1–0 defeat away to Notts County.He sustained a knee injury during a 1–0 home win over Darlington on 29 October 2005, which resulted in him being substituted in the 31st minute.