A solid revenue report was not enough to prevent stock at Twilio from plunging in trading after hours. What appeared at first glance to be a good story very quickly became a financial nightmare for the company.

The cloud communications business saw its stock fall by 30% during trading afterhours that was attributable to guidance that was lower than anticipated.

During a conference call for earnings, CEO Jeff Lawson spoke about the unexpected guidance. He explained that Uber, one of the largest customers of Twilio, will be reducing use of Twilio during the next year.

That is a huge hit for the business since Uber represented over 12% of overall revenue during the just ended quarter. The company is expecting that number to drop off during the next year due to Uber moving away from using it as a principal provider of communications infrastructure.

Guidance was issued by Twilio indicating revenue would be $356 million to $362 million for the full year. That falls short of Wall Street expectations of just over $370 million.

For 2017 second quarter earnings, Twilio issued a new guidance saying it expected revenue of $85.5 million to $87.5 million. Wall Street anticipated revenue would be $87 million at the low end, but as the high-end of the revenue target.

Outside of its guidance, Twilio posted revenue for the quarter of $87.4 billion with a non-GAAP loss of 4 cents per share for its 2017 first quarter.

That beat expectations by analysts of $83.5 million and beat an expected loss of 6 cents a share.

Twilio has struggled for some time with customer mix and it has now come back to hurt them. Large clients such as Uber or WhatsApp have made up large amounts of the revenue of the company, causing anxiety for some on Wall Street.

However, while Twilio has moved to diversify its revenues stream, one customer, Uber in this case, was able to extract close to $1 billion in its market value.

CEO Lawson explained that WhatsApp and Uber are the two biggest Twilio clients by a large margin. Twilio added over 4,000 new clients during the first three months of 2017 and has traditionally had an average net gain of clients per quarter of 2,800.

Twilio is still in its early stages of development as a company and CEO Lawson has been impressive in building it.