MEDAN, Indonesia — A High Court on Thursday upheld an 18-month prison sentence for a woman convicted of blasphemy in Indonesia after complaining about the volume of a mosque’s loudspeakers.

The woman’s lawyer, Ranto Sibarani, said the decision would be appealed to the Supreme Court.

The ethnic Chinese woman, Meiliana, was sentenced in August, more than two years after her comments sparked rioting in her hometown of Tanjung Balai on the island of Sumatra.

In a conversation with the daughter of the caretaker of her neighborhood mosque, Meiliana had commented that the five-times-daily call to prayer was too loud.

Rumors then spread that she wanted to stop the call to prayer and days later, mobs attacked her home and burned and ransacked at least 14 Buddhist temples.

Indonesia’s largest Muslim organizations have said her complaint wasn’t blasphemy and have criticized her imprisonment but a conservative group, Islamic Community Forum, said Meilana’s sentence was too light.

The case has highlighted how Indonesia’s blasphemy law has become a tool for Islamic hard-liners to persecute followers of minority religions in the world’s most populous Muslim nation.

Meiliana, who uses a single name, wasn’t in court for Thursday’s decision.

Her supporters say she is kept in a 323-square-foot cell with more than a dozen other women.