West said Wednesday in a tweet that he would open 21 pop-up stores in cities including San Francisco, New York, Atlanta, Paris, Berlin, Sydney, and Miami to sell t-shirts, hoodies, and jackets branded with Life of Pablo, his latest album. Those in U.S., Canada, and Australia would use Square, he said.

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While the stores are only open for one weekend, Square could end up processing a huge number of payments. A Life of Pablo pop-up store in New York City earlier this year reportedly handled more than $1 million in business over one weekend.

Square’s co-founder and CEO Jack Dorsey, who also serves as the CEO of Twitter, is known for his close ties to celebrities. While it’s unclear if West is part of his posse, Dorsey has tweeted back and forth with West in the past, and has done the same with West’s reality TV star wife.

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Square has been the exclusive point sale technology at a number of major music festivals this year including BottleRock in Napa Valley, Coachella near Palm Springs, Calif., and Panorama in New York. Some of these festivals generated $1 million in payments in a weekend.

In its most recent earnings report, Square said that the amount of payments made through its credit card readers was up 42% to $12.5 billion in the quarter. Part of that is attributed more larger sellers with more than $125,000 in yearly payments using the service. Their number grew 61% year over year, representing 42% of total volume for Square in the second quarter of 2016. That’s up from 37% of volume in the second quarter of 2015.