It’s been a rough road for Chinese EV startup Nio, and it looks as though things are about to get even bumpier. On Thursday, Nio confirmed that co-founder Jack Cheng is leaving, five years after he helped start the company.

Cheng was an integral part of Nio’s early success, with the executive providing a wealth of knowledge from his time as head of Ford’s Chinese operations. It was on Cheng’s watch that Nio launched its first production model, the ES8 mid-size SUV, and went public on the New York Stock Exchange.

But the last year has been a difficult one for Nio. After strong initial sales in China, demand for the ES8 has plummeted. As a result of the ES8’s poor sales, Nio has been forced to layoff employees, close its Silicon Valley office and delay the introduction of a promised electric sedan.

Nio ET Preview concept

Nio ET Preview concept

Things clearly aren’t going swimmingly for the EV maker, but Nio says Cheng’s retirement has nothing to do with the company’s recent poor performance. A company spokesperson told The Verge that Cheng, 61, opted to retire “due to age.”

Whatever the case, Cheng will miss the chance to oversee the company’s new ES6 SUV, which went on sale in June. Nio has only sold 1,086 units of the ES6 during its first two months on the market, but that’s a far better clip than the 164 ES8s Nio delivered in July.

William Li and Lihong Qin, the company’s other co-founders, are still on the team. Li currently serves as CEO while Qin holds the title of president.