Anheuser-Busch is suing Constellation Brands over its use of the “Corona” name for a brand of increasingly popular hard seltzer.

The suit was filed in federal district court by Grupo Modelo, the Mexican unit of Anheuser-Busch InBev. Anheuser-Busch sold Constellation the rights to make and distribute Corona beer in the U.S. in a divestiture to satisfy antitrust regulators when it bought out Grupo Modelo in 2013.

Anheuser-Busch contends that that deal did not give Constellation the right to apply the Corona name to non-beer beverages. Corona Hard Seltzer, rolled out early last year, now has about a 6% of the market for hard seltzer, one of the fastest-growing beverages in the U.S.

Anheuser-Busch makes Bud Light Seltzer, which is now the No. 3 U.S. brand of hard seltzer. Corona Hard Seltzer is No. 4.

Anheuser-Busch said that it had tried to work out the issue with Constellation before filing the suit. For its part, Constellation said it was surprised by the suit and that it has “fully and completely” complied with the licensing agreement.