A delay to Brexit would be a "further annoyance" which would prolong uncertainty, the boss of luxury carmaker Aston Martin said.
His comments come after Prime Minister Theresa May promised to give politicians a vote on extending the date Britain leaves the EU.
Many firms have been triggering contingency plans on the assumption that Britain will leave the European Union on March 29, though a delay could scupper the timing of those preparations.
Aston Martin, which has authorised up to £30m worth of contingencies, has been boosting the level of components it holds.
UK politicians will vote on whether to delay Brexit on March 14, just over two weeks before the scheduled departure date.
"I would categorise it as a further annoyance," the company's chief executive Andy Palmer said.
"You're holding that contingency stock for longer which means that your working capital is tied up for longer. More importantly, what you're doing is you're creating continued uncertainty," he said.
Aston Martin floated on the London Stock Exchange last year and is boosting its volumes and building its first sport utility vehicle at a new factory.
Today it posted a 26% rise in 2018 volumes and a 25% increase in revenues.
Adjusted pre-tax profits fell 7% to £68m before one-off costs related to its initial public offering.
The company said that if some one-time pension-related credits were stripped out of 2017's figures, adjusted pre-tax profit would have risen in 2018.
Britain's once-soaring car industry is now recording falling sales, investment and production, with Honda delivering the most serious blow earlier this month, announcing the closure of its British factory.