An advertising campaign for Shell featuring a giant red ball has one artist feeling blue. The Guardian reported that Kurt Perschke is alleging the petrochemical giant lifted the idea for their recent campaign from his RedBall Project. Big balls are Perschke’s bailiwick: the man has been depositing his sanguine spheres in public places the world over for 13 years, with the effort documented in photographs posted on his website.

Shell denied the similarities were tantamount to theft, or even inspired by the artist’s work. Through a spokesperson, the company told the Guardian that their “campaign uses imagined illustrations of a red sphere in iconic locations. They are not actual or physical installations of red balls, which is the focus of the artist’s installations.” The company further pointed out that the use of inflated spheres to represent carbon dioxide is a common practice.

But Perschke is adamant that the advertisement in question, which is set in London’s Trafalgar Square, is derivative, even following on the heels of his work’s recent appearance in the city. “They could have done it a lot of ways, it could have been a balloon or a kickball or a football or whatever but it’s not, it’s spot on and because we were in London so recently it is frustrating and disheartening,” he told the Guardian.

The courts have sided with Perschke in the past: Last year, the Guardian notes, Perschke successfully obtained a settlement from French logistics company Edenred over their apparent copyright-infringing use of red balls in ads. (That case was filed in New York’s Eastern District court; it’s unclear if Perschke has access to a jurisdiction in which he could file against Shell.)

A small critical footnote: If you make art that is easily duplicated as generic corporate messaging, you should worry more about the possibility of your art being terrible and less about getting ripped off in an advertisement.