A Singapore couple is challenging a decision by the government to annul their marriage after one of them transitioned.

Authorities voided the marriage of Faith and Bryce Volta last year, arguing that their union had become a same-sex marriage when Faith underwent gender-confirmation surgery and updated her national ID to read "female."

Six months after Faith's transition, the couple were contacted by the Registrar of Marriages, who informed them of the annulment. The Voltas are now asking the High Court to review the decision, according to attorney Eugene Thuraisingam, who is representing the couple pro bono.

Marriage equality is not recognized in Singapore, as Prime Minister Lee Hsien Loong has said he does not believe the country is ready for it. Same-sex relations between men are technically illegal, although violators are rarely charged.

The city-state also lacks anti-discrimination laws protecting sexual minorities in employment and housing.

Still, there is a growing call for LGBT rights: In 2017, more than 20,000 people attended Pink Dot, Singapore’s annual LGBT Pride celebration, despite government regulations barring foreigners and multinational corporate sponsors.