U.S. sprinter Sha’Carri Richardson is calling out Olympic and anti-doping officials, after Russian skater Kamila Valieva was allowed to compete despite testing positive for a banned drug. “Can we get a solid answer on the difference” between their situations? Richardson asked on Twitter, after mediators ruled that Valieva should be allowed to skate in the women’s individual competition in Beijing. “The only difference I see is I’m a black young lady,” Richardson said. “It’s all in the skin,” she added.

Richardson won the 100-meter race at the U.S. Olympic trials early last summer, but after it was revealed that she had tested positive for THC, the intoxicant in marijuana, she was denied a chance to compete at the Tokyo Olympics. THC is on the World Anti-Doping Agency’s list of prohibited substances — but so is trimetazidine, the drug that was found in Valieva’s test sample. The heart drug is believed to be able to boost athletes’ endurance and blood efficiency. In other words, it can boost athletic performance, while THC does not. Richardson pointed out that difference in her tweets responding to the ruling on Valieva’s eligibility at the Winter Olympics. Richardson, who like Valieva was favored to win a medal in her sport, also noted a stark difference in how their positive tests were handled. While the Russian star failed a test that was submitted in December, she somehow avoided a suspension.