The student leader on Tuesday posted on Twitter a message he said he’d received from Google warning that hackers supported by unspecified authorities may have been trying to steal his Gmail password and access his data.

“There’s a chance this is a false alarm, but we believe we detected government-backed attackers trying to steal your password,” the message read. “This happens to less than 0.1% of all Gmail users.”

It’s not unusual for Google to warn Gmail users about possible break-in attempts, which it says it’s been doing since 2012 “out of an abundance of caution.” The internet giant pulled its search service from mainland China in 2010, citing censorship as well as concerns about potential state-backed hacks into Chinese activists’ accounts.

Representatives for Google didn’t immediately respond to requests for comment outside of normal U.S. hours.

Wong, a former student leader, co-founded the small pro-democracy Demosisto party and rose to prominence as the face of the 2014 Occupy movement that brought parts of Hong Kong to a standstill.

After serving a month in jail on charges relating to his involvement with Occupy, Wong left prison last month and said he would join the current protests, which have seen hundreds of thousands of people march against proposed legislation that would allow extraditions to China.