JAKARTA (Reuters) – Indonesia’s Supreme Court has upheld a jail sentence for a mother of four who was convicted last year on blasphemy charges for complaining that her neighborhood mosque was too loud.

In a March 27 ruling posted on the court’s website on Monday, the court rejected the appeal by Meliana, a 44-year old ethnic Chinese, Buddhist resident of Medan on Sumatra island.

Indonesia has the world’s largest population of Muslims, and sizable Buddhist, Christian and other religious minorities, but the propagation of conservative and hardline interpretations of Islam in recent years has fanned fears that the secular nation is becoming less tolerant.

“This is another nail in the coffin of religious freedom and tolerance in Indonesia because of institutionalized discrimination,” said Andreas Harsono of Human Rights Watch.

Meliana’s lawyers said she had made remarks in a private conversation in 2016 on the volume of mosque loudspeakers. Those remarks were twisted to appear like she was objecting to the call to prayer itself and repeated in the community and on social media, her legal team said.

Meliana is serving an 18-month sentence in a Medan prison.

Senior members of Nahdlatul Ulama (NU), the country’s largest moderate Muslim organization, have said her remarks should not be considered blasphemy.

There are hundreds of thousands of mosques across the vast Indonesian archipelago and most use loudspeakers to play the ‘azan’ or call to prayer, which lasts a few minutes.

But many also play lengthy versions of prayers or sermons lasting over 30 minutes, which the Indonesian Mosque Council has deemed unnecessary.

Reporting by Agustinus Beo Da Costa and Kanupriya Kapoor; Writing by Kanupriya Kapoor; Editing by Darren Schuettler