Hong Kong’s bid to wipe a controversial protest song from the city’s internet is flashing fresh warnings signs for businesses that the once-freewheeling international hub is tracking closer to mainland rules.

The city’s High Court on Friday heard the government’s argument for why it should be illegal to perform or broadcast Glory to Hong Kong with criminal intent. That case has raised fears that Western tech firms such as Alphabet’s Google, which has already quit China over censorship, may be forced to reconsider their presence in the city. Many versions of the song have already disappeared from online platforms such as Apple’s iTunes and Spotify.

Government prosecutors argued the tune’s proliferation online was a matter of national security that would plant seeds of secession, an offense under a Beijing-drafted law carrying sentences as long as life in prison. The judge set a July 28 date for handing down a decision.