Blue Öyster Cult singer Eric Bloom will miss some of the band’s upcoming shows after undergoing a non-life-threatening surgical procedure, leaving Kasim Sulton to fill in for a few dates as the group returns to the road.

Bloom said on May 13 that he had arranged the procedure during the band’s time off and that his recovery was taking longer than he expected. “I am on the mend, but the recovery is taking a little longer than expected,” he said. “Kasim Sulton will be standing in for me for a few shows and knock it out of the park!”

The band’s next scheduled performance is May 16 in Oroville, California, and additional dates run through the summer and fall. Blue Öyster Cult’s most recent concert was on February 26 aboard the Rock Legends Cruise, so the change comes just as the 81-year-old frontman is set to rejoin a busy touring stretch.

Sulton is no stranger to the group. He served as Blue Öyster Cult’s bassist and backing singer from 2012 to 2017, and he is best known for his work with Utopia. He has also performed with Meat Loaf, Hall & Oates, Cheap Trick, Patty Smyth, Akiko Yano, Richie Sambora and Todd Rundgren, and sang lead on Utopia’s “Set Me Free,” the band’s only U.S. top 40 hit. As a solo artist, he reached the Canadian top 40 in 1982 with “Don’t Break My Heart.”

The temporary lineup change does not alter the larger picture for Blue Öyster Cult, a band still active well into its later decades and still drawing on a catalog that has made it a touchstone for hard rock acts, including Metallica. For now, Bloom’s message makes the situation plain: he expects to be back, but a few dates will go on without him.