Out British singer Sam Smith has called on Australians to “change for the better” as voters there begin casting their votes on whether same-sex marriage should be legalized.

The Australian government is spending an estimated $122 million on a postal survey which asks, “Do you support a change in the law to allow same-sex couples to marry?” Participation in the survey is non-compulsory and the results are not binding.

The 25-year-old Smith responded to a skywriting stunt over Sydney urging voters to “vote no” on same-sex marriage.

“Can't believe my eyes,” Smith tweeted to his more than 4.74 million followers on Sunday. “'Vote No' being written in the sky over Sydney from people against equal marriage.”

“Come on beautiful Australia.... Let's change things for the better. LOVE LOVE LOVE is LOVE.”

Smith returned to social media earlier this month to promote his first single in two years, Too Good at Goodbyes. He has also confirmed that his as-yet titled sophomore album will arrive before Christmas. Smith's debut album, In the Lonely Hour, was named Best Pop Vocal Album at the Grammys in 2015.

(Related: Sam Smith tells Elton John that he came out when he was 10.)