Jemima Sumgong, who became the first Kenyan woman to win a Olympics marathon gold at Rio 2016, has failed an out-of-competition dope test.

The 32-year-old, who is also the reigning London Marathon champion, tested positive for the banned blood booster EPO in a test by the International Association of Athletics Federations in Kenya, BBC reported.

“We can confirm that an anti-doping rule violation case concerning Jemima Sumgong has commenced this week. The athlete tested positive for EPO following a no-notice test in Kenya,” the IAAF said in a statement.

Sumgong starred at the London Marathon last year, defying the odds to win despite a bruising fall. After her success in London, she went to become the first Kenyan woman to win Olympic marathon gold, defeating Ethiopia’s world champion Mare Dibaba in Rio.

Before claims of a positive drugs test emerged, Sumgong had said she was looking forward to returning to London to defend her title on April 23. “London is the marathon every runner wants to win. I can’t wait to return to defend my title,” she had said.

Earlier this year, Sumgong was part of a number of top Kenyan athletes who welcomed a new initiative to stop doping, which has tarnished their image, in which they agreed to be monitored by doctors appointed by the IAAF and Athletics Kenya.

“It will be easy for us now to communicate with these doctors before we take any medicine when the need arises,” Sumgong had said.

News of Sumgong’s test was welcomed by other athletes. US distance runner Emma Coburn, a bronze-medallist in the 3,000m steeplechase at last year’s Olympics, applauded the IAAF’s out-of-competition testing on Twitter.