Earlier this week, Ming-Chi Kuo, a KGI Securities analyst with a reliable reputation for Apple leaks, warned that only a premium iPhone Plus model next year would include a superior OLED screen, while other models would continue with older LED screens.

Now comes some further explanation of why Apple would leave out one of the most desired new features from most 2017 models. Manufacturing OLED screens is difficult and Samsung, Apple’s supplier, will not be able to produce enough to meet demand for all iPhones next year, Bloomberg reported on Thursday citing anonymous sources. Other possible OLED screen suppliers LG Display, Sharp, and Japan Display are also supply-constrained, the news service added.

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Fortune reached out to Apple for comment and will update this story if a response is received.

The supply crunch means Apple may not be able to entice or satisfy as many iPhone upgraders as analysts had anticipated. After this year’s iPhone 7 line basically retained the same exterior design and screen technology as models from the prior two years, analysts expected many Apple fans would wait until next year to upgrade.

Apple (AAPL) is expected to unveil an iPhone with a completely redesigned exterior and many new features next year. Prior rumors suggested that the new iPhone will have an edge-to-edge display, eliminating the bezel, and a virtual on-screen home button.

Apple has improved the iPhone’s screen somewhat in recent years by increasing the range of colors it can show, making photos appear more lifelike for example. But the iPhone’s screen resolution of 750 pixels by 1334 pixels has not changed in the past three models.

Meanwhile, competitors like Samsung (SSNLF) have been adding more pixels and using OLED to display sharper on-screen images, a far more noticeable upgrade than Apple’s color range improvement.