Great Britain's Mallory Franklin won her first World Cup gold medal of the season with victory in Pau, Spain.
Franklin, competing the day before her 22nd birthday, had originally been awarded C1 silver behind Jessica Fox.
Judges later reversed their positions after adding a two-second penalty to the Australian world champion's time for hitting gate three.
The women's C1 is not an Olympic event but is being proposed for inclusion in the 2020 Tokyo Games.
"It was a bit of a struggle for everyone in the final," said Franklin, who won gold ahead of Fox when London hosted the World Cup in 2014.
Compatriot Adam Burgess, the world under-23 champion, was sixth in the men's event.