In a note to investors on Tuesday, GBH Insights analyst Daniel Ives said that he expects worldwide iPhone X pre-orders to top 40 million units. While that might sound like good news for Apple, there’s a problem: the company might only have 20 million iPhone units available to customers over the next few months, according to Ives. If that’s the case, he believes Apple won’t catch up to demand until April or May of next year.

Apple unveiled its iPhone at a press event last month. The device comes with a major redesign, including a screen that nearly entirely covers its face, wireless charging, and a new Face ID scanner to verify a person’s identity and give him or her access to the smartphone’s software. Apple has called the iPhone X the “future” of smartphones.

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Since then, market reports on customer demand has suggested that consumers are far more interested in the iPhone X than the iPhone 8 and iPhone 8 Plus that were announced alongside the iPhone X.

Meanwhile, Apple (AAPL) has reportedly been hobbled by manufacturing problems that have slowed down the process of getting iPhone X units off its assembly lines. Chief among those problems has been a sensor built into the smartphone that allows its Face ID function to accurately identify a person’s face, according to reports.

Last week, KGI Securities analyst Ming-Chi Kuo told investors in a note that Apple’s assembly partners have worked out the problems, and are now manufacturing units more quickly. However, he reduced his shipment prediction on available units through the end of the year from an estimated 30 to 35 million to 25 million to 30 million. He also said Apple might only have 2 million to 3 million iPhone X units available by the smartphone’s November 3 release date.

Ives said that he, too, is hearing that iPhone X production is “modestly improving,” but has apparently done little to affect “a 2:1 ratio of demand over supply globally for iPhone X.”

For investors, Ives said, it’s not all bad news that Apple won’t be able to handle demand. He said that a “super cycle” of widespread iPhone upgrades to the iPhone X is still happening, but won’t occur “overnight.” Instead, he believes investors will need to have “patience” as Apple works through its iPhone X supply problems.