In 2017, his cover of "Big Jet Plane" by Angus and Julia Stone with the Brazilian DJ Alok peaked at number one in Brazil and in the top 10 in multiple European countries.
[citation needed] In 2020, his collaboration with Belgian DJ Lost Frequencies, "Don't Leave Me Now," will receive a Platinum record in Belgium.
Koss's collaboration with Alok, "Big Jet Plane",[2] peaked at 19th on the Belgian Wallonia Tip chart.
March 2019 Mathieu release Never Growing Up with the American singer Aloe Blacc.
The same year Mathieu receive a Platinum Record for "Don't Leave Me Now" his collaboration with the Belgian DJ Lost Frequencies.