Micron Technologies (MU) reported fiscal fourth quarter results on Thursday after the markets closed and initially appeared to deliver an excellent quarter.

MU posted net earnings of $3.53/share versus the Zacks Consensus Estimate of $3.32 and revenues of $8.44B – a 38% increase over Q4 2017. Full fiscal year results showed revenues up 50% and operating cash flow that more than doubled over fiscal 2017.

President and CEO Sanjay Mehrotra Commented “Micron delivered an exceptional fourth quarter and capped record fiscal year results by becoming the second largest semiconductor company in the U.S. In the fourth quarter, we set revenue records across all major markets, from automotive and industrial to mobile and cloud datacenters.”

Micron shares initially rallied in after-hours trade.

Then came the guidance.

Micron estimated that future quarterly revenue would likely be between $7.9B and $8.3B, short of the expected $8.45B. Future quarterly net earnings were predicted to be $2.87 – $3.02/share, below the high estimate of $3.08/share, though in line with the Zacks Consensus estimate for the current quarter of $2.88/share.

Micron also noted the potential impact of the most recent round of U.S tariffs which are set to start at 10% and go into effect on September 24 and will increase to 25% at the beginning of 2019 if a trade agreement with China is not reached by then.

On the investor conference call, Micron CFO David Zisner noted that gross margins will be impacted in the near term and that “We are working to gradually mitigate most of the impact from these tariffs over the next three to four quarters. Clearly, tariffs are affecting us, probably to the tune of 50 to 100 basis points. We are working on steps to mitigate that. That obviously takes time.”

Micron also confirmed that PC processor shortages could hurt demand for memory chips. It had been previously reported that a manufacturing change at Intel (INTC) could potentially slow production of the company’s CPUs, which could slow global production of PCs, hurting the sales of makers of other components, like Micron.