Apple is working to match the demand for the iPhone 7 Plus as best as it can, but it might not meet all the demand by the end of the year, CEO Tim Cook said on the investor call discussing its fourth-quarter earnings.

“It’s hard to say,” Cook said in response to an investor question about whether the iPhone would hit supply/demand equilibrium by the end of the next quarter. “I believe that on iPhone 7 we will, on iPhone 7 Plus I’m not sure. I wouldn’t say yes at this point because the underlying demand looks extremely strong on both products but particularly on the iPhone 7 Plus vs our forecast going into the product launch.”

This is going to be a very big deal for Apple, which is looking for its first return to sales growth in the first quarter this year. The holiday quarter is critical for Apple, and in addition to that it has a huge window of opportunity given that the Galaxy Note 7 is basically dead in the water.

“It’s very hard to gauge demand when you’re selling everything you’re making, so we’ll find out more through the quarter but we’re confident enough to give you guys guidance that we’re returning to growth this quarter, which obviously feels very good for us,” Cook said.

Apple’s iPhone sales have not only been slowing, but declining, year-over-year in several quarters this year. That’s largely been attributed to an overall saturation of the smartphone ecosystem, especially since Apple largely targets a higher-end part of the market. Apple is also seeing a lot of competition from other manufacturers trying to beat it at a lower price point.

“We are supply constrained on 7 and 7 Plus, when you talk about other competitors it’s not particularly relevant to us right now because we are selling everything we can produce,” Apple CFO Luca Maestri said. “When we look at all these things in its totality, we think for the total company, we believe revenue is gonna grow. We don’t get into specific product from a unit standpoint giving guidance. We feel very confident for the trajectory of iPhone going forward.”

Already, the iPhone 7 Plus is seeing massive shipping delays because its demand has drastically outstripped its supply. If you try to go purchase an iPhone 7 Plus, the shipping delay may be as high as several weeks. Apple is frantically trying to make as many iPhone 7 Plus phones as it can, and it’s going to be critical that it finds a way to meet that demand.

The exact question from the analyst was, “in terms of supply, do you think we’ll be at equilibrium by the end of the quarter?”