A voluntary public good is a non-rivalrously-consumed commodity which, nonetheless, individuals can only consume if they make some enabling expenditure. E.g., with visual broadcasting a television is required and, in much of Europe, a licence. First, we characterise the population of voluntary consumers at arbitrary levels of the licence fee. Next, we consider the optimal licence fee chosen by a utilitarian government which recognises it does not have a captive population of public good consumers. We compare this outcome with that arising when the public good is financed from general taxation via a uniform poll tax and thus everyone consumes it.