Mowbray said that injury had disrupted Fortune’s season but that he hoped the £3.8million signing was going to go on a goal-scoring run.
"Hopefully this will kick-start him, he has had a frustrating time,” Mowbray told Sky Sports.
"He came back and found himself on the bench but every time he's come off the bench he has sparked the team and I hope for more of those goals."
Fortune’s 25-yard strike saw Celtic come out on top in an exciting match that saw the visitors come back from a 2-1 half-time deficit.
Mowbray admitted however he was frustrated by his side’s defensive lapses.
"We thought (the problems) had gone away over the last few weeks,” he confessed.
"The first goal is from nothing, they dug a cross out right from the corner flag and the second one was bread and butter for us.
"They don't need me to tell them that they need to tighten up because the play going the other way has been very good in the last three or four weeks."