The canonization of Carlo Acutis, the Catholic Church’s first millennial saint, will take place on September 7, Pope Leo XIV has announced. Acutis, an Italian teenager who died from leukemia in 2006, will be declared a saint by Leo at a ceremony in St. Peter’s Square expected to be attended by thousands of young people. Acutis was just 15 when he died, but during his short life he used his computing skills to spread awareness of the Catholic faith by setting up a website that documented reports of miracles.

The Vatican said on Friday that following a meeting with cardinals Pope Leo will canonize Acutis in September, along with another youthful saint, Pier Giorgio Frassatti, who died in 1925 at age 24. Acutis’ canonization had been scheduled for April 27 but was postponed after the death of Pope Francis.