I'm using Rails 3.0.0.beta3 and Haml 3.0.0.rc.2, and I can't find where I need to place the configuration lines for Haml (nor what they are in the new version, for that matter). Using Rails 2.3.5 and Haml 2, I would do Haml::Template.options[:format] = :html5 in environment.rb. Or, in Sinatra, set :haml, {:format => :html5} in my main file. But in Rails 3 everything's been changed around, and no matter where I put that configuration line, I get an undefined method or undefined object error.