The Northern Irish U21 international has played well in his games for Partick and will stay at Firhill until June 2009.
Manager Dick Campbell told the Partick Thistle official website:" I really do rate Johnny. I would say he is the best 'keeper I have seen at his age, remember he is only 19, and I predict that he will have a really bright future ahead of him. Every manager will tell you that he wants two good 'keepers to fight for the number one jersey and I am convinced we now have that here with both Kenny and Johnny more than capable of playing in the first team and I would expect both to be able to perform at the highest level when we are fortunate enough to get there. I feel that this a great bit of business for Partick Thistle and look forward to working with him over the next few seasons."
Meanwhile, Rikki Bains has been loaned out to Leek Town by his current club Accrington Stanley.