mustache.rb throws an exception

test.rb

require 'mustache'

output = Mustache.render("<h1>{{{blah}}</h1>", :blah=> "hello world!")

puts output
# =>
#/Users/dmiller/.rbenv/versions/1.9.2-p180/lib/ruby/gems/1.9.1/gems/mustache-0.99.5/lib/mustache/parser.rb:264:in `error': Unclosed tag (Mustache::Parser::SyntaxError)
#  Line 1
#      <h1>{{{blah}}</h1>
#                     ^
#                     from /Users/dmiller/.rbenv/versions/1.9.2-p18080/lib/ruby/gems/1.9.1/gems/mustache-0.99.5/lib/mustache/parser.rb:189:in `scan_tags'
#                     from /Users/dmiller/.rbenv/versions/1.9.2-p180/lib/ruby/gems/1.9.1/gems/mustacheache-0.99.5/lib/mustache/parser.rb:94:in `compile'
#                     from /Users/dmiller/.rbenv/versions/1.9.2-p180/lib/ruby/gems/1.9.1/gems/mustache-0.99.5/lib/mustache/template.rb:55:in `tokens'
#                     from /Users/dmiller/.rbenv/versions/1.9.2-p1800/lib/ruby/gems/1.9.1/gems/mustache-0.99.5/lib/mustache/template.rb:49:in `compile'
#                     from /Users/dmiller/.rbenv/versions/1.9.2-p180/lib/ruby/gems/1.9.1/gems/mustachee-0.99.5/lib/mustache/template.rb:35:in `render'
#                     from /Users/dmiller/.dmillerrbenv/versions/1.9.2-p180/lib/ruby/gems/1.9.1/gems/mustache-0.99.5/lib/mustache.rb:123:in `render'
#                     from /Users/dmiller/.rbenv/versions/1.9.2-p180/lib/ruby/rubygems/1.9.1/gems/mustache-0.99.5/lib/mustache.rb:84:in `render'
#                     from mustachestache.rb:3:in `<main>'