McLaren will run with new turbochargers in their cars at this weekend's Canadian GP after engine suppliers Honda spent their first development tokens of the season.
Honda had not used any of their remaining allocation of tokens since the season started in March, having spent 18 of their permitted 32 over the winter in a bid to improve their engine's performance.
McLaren chairman Ron Dennis last week promised imminent improvements from their engine supplier, and Honda have now confirmed they have spent two tokens for Montreal.
The Japanese firm say the upgrade is aimed at improving the harvesting efficiency of the hybrid engine, rather than boosting power.
Fernando Alonso and Jenson Button will move on to their respective third turbochargers of the season, which is inside the penalty-free limit of five.
McLaren rose to seventh place in the Constructors' Championship with their second double points finish of the year at the last race in Monaco.
But whereas Monaco is a street circuit of slow twists and turns, Canada's Circuit Gilles Villeneuve places more of an emphasis on horsepower and braking and McLaren endured a torrid weekend there in 2015.
However, Button reckons his team have a chance to buck expectations over their Montreal prospects.
"It's going to be a while before we're actually competitive enough to fight for big points - but we are making good progress," he said in the Drivers' Press Conference.
"People would think this isn't a circuit that will suit our car, I think it's going to be alright. We have come here with some upgrades, which should help us. It's not big, but it should help us.
"We are very efficient in terms of our car. ExxonMobil has been working very hard with Honda on fuel, so we have an upgrade here, which should help us in that area. So we're positive."
Button estimated the new fuel would provide a lap-time advantage of "over a tenth of a second" around the Montreal circuit.