Arcade Fire frontman Win Butler says he had to wear a denim "Canadian tuxedo" and assured fans that Mounties are real in a social media post announcing his Canadian citizenship.

The Instagram post shows Butler standing behind a cake decorated like a Canadian flag alongside officials, an RCMP officer and others during the ceremony.

Butler says he has lived in Montreal for half of his life so it feels "very natural" to hold both Canadian and American passports.

Citizenship Minister Ahmed Hussen is shown in a second post saying he believes Montrealers have "very much" adopted Butler and he has adopted Montreal.

He says the members of Arcade Fire have made "extraordinary contributions" to a number of humanitarian causes over the years, including supporting health care improvements in Haiti.

Hussen says those efforts have had a long-lasting positive impact not only in that country, but in the larger Haitian community in Canada.

In 2017, Butler and Arcade Fire's co-founder and Butler's wife Régine Chassagne were recognized by Quebec's government for their roles as cultural ambassadors for the province.

The vocalists were among 18 honourees to receive the year's Companion of Quebec's Order of Arts and Letters, a recognition for "outstanding contributions to the diversity and vitality of Quebec culture."

Butler has also not been shy to make his political views known.

During a early private industry ceremony held for the 2018 Juno awards, he acknowledged the student-led protests which were taking place across the U.S. at the time and elsewhere calling for gun control.

"I just want to give a shoutout to our brothers and sisters down south," Butler said onstage. "Canada is just such a beautiful example of how it doesn't have to be like that."

He added backstage about the rallies: "I hope that we can continue to persist."