Grunt-Spritesmith: How can I lowercase the file name in the handlebar template?

Question

I have this:

{{#items}}
  .ts-{{name}} { background-position: sprite_position_percentage( {{px.offset_x}}, {{px.offset_y}} ) }
{{/items}}

How can I lowecase the name variable?

I tried {{name.toLowerCase()}} but the output produced was missing the name parameter: .ts- { background-pos...