Zimbabwean pastor Evan Mawarire has been charged with attempting to overthrow the government through an internet campaign that inspired rare protests this month against President Robert Mugabe.
Mr Mawarire appeared in a packed Harare courtroom on Wednesday draped in the Zimbabwean flag after spending the night in police cells as officers searched his house, church and office.
Mr Mawarire's lawyer Harrison Nkomo said his client faced up to 20 years in jail and accused the state of ambushing the defence by changing charges without informing them.
Hundreds of Mr Mawarire's supporters gathered outside the court, waving the national flag and singing protest songs, as anti-riot police kept a watchful eye.
"We are here in solidarity with a man of the cloth who is standing against a system that has impoverished the citizens of this nation," Harare resident Pastor Ellard said.
Though Mr Mawarire had called for further "stay at home" protests on Wednesday, queues built up as normal at bus and taxi ranks to ferry people to work, while most businesses were open.
Teachers reported for duty at most public schools, which are conducting mid-year examinations, while nurses and doctors were at work at state-run hospitals.
Mr Mawarire last month posted a video online, that has since gone viral under the moniker #ThisFlag, venting his anger about deteriorating social and economic conditions in Zimbabwe and urging citizens to hold government to account.
"I am angered by the poverty and day to day struggles. The economy is not working and there are no jobs," Zimbabwean activist Maureen Kademaunga told Reuters.
The preacher's social media movement has rattled 92-year-old Mugabe's administration, leading to accusations by the state against Mr Mawarire of inciting public violence.
Zimbabwe's government warned protesters on Tuesday they would face the "full wrath of the law" if they heeded Mr Mawarire's call, after his #ThisFlag movement organised the biggest anti-government demonstrations in a decade last week.