Apple had a pretty good quarter — the stock just jumped 4 percent after hours on $45.4 billion in revenue and earnings per share of $1.67.

But there’s one dark spot in the company’s results — and that’s performance in Greater China.

Apple took in just over $8 billion in revenue from Greater China this quarter, which is less than half of what it made there two years ago in Q2 2015. It’s also a 10 percent decline year-over-year and a 25 percent decline from last quarter. To compare, revenue generated in the Americas was up 13 percent year-over-year, and down only 4 percent from last quarter.

Greater China is also the only region that saw negative growth year-over-year.

At least Apple seems to be aware of, and working on, the issue. A few weeks ago the company appointed its first-ever managing director of Greater China, who will report directly to CEO Tim Cook and COO Jeff Williams.

China was once a bright spot for Apple, and the fastest-growing region for the company. Q2 2015 saw $16.8 billion in revenue from China. Two years later, the company is now making less than half of that.

On the earnings call, Apple CEO Tim Cook explained that Hong Kong continues to drag down revenue for all of Greater China, and what they see from the mainland is more encouraging. Cook also said he thinks the popularity of WeChat and other messaging services is a good thing and makes it easier for potential new customers to switch to iOS, because the platform works on iPhone and users’ old phones.