Can't render literal templates

[00-FF-FF]

Hi, I can't seem to manage to render a template from a string variable, it just tries to find a file with that name.

mustache "Hello World"

gives an error page:

Errno::ENOENT at /page
No such file or directory @ rb_sysopen - path/to/sinatra/views/Hello World.mustache
file: settings.rb location: read line: 142

whereas

erb "Hello World"

works as expected and prints "Hello World" to screen

Apologies if I'm missing something obvious but I've searched at length and haven't managed to find anything that could help me.