(CNN) The most decorated Olympian of all time thinks it is a "joke" athletes who were banned for doping could still compete against him in major finals.
Michael Phelps, who won a record 23 gold medals in an astonishing career, wants swimmers who use banned substances to be thrown out of the sport for good.
The 31-year-old recently told a US congressional hearing on improving anti-doping measures "the time to act is now." And he reiterated that stance when speaking to CNN's Coy Wire.
READ: Phelps 'never competed against clean international field'
"There were people who had tested positive not once but twice who were able to compete and that's a joke," he said.
"Especially as a father now, with Boomer growing up -- I don't ever want him to see that world.
"It's not what sports is all about and hopefully someone can change that."
Phelps also confirmed he would not be coming out of retirement, ruling out a return to the sport in time for the Tokyo Olympics in 2020.