Uninitialized constant YARD::Parser::CParser in yard_ext.rb

[samkellett]

When trying to generate the documentation with yard I get the following error:

Sams-Air:ray samkellett$ yard doc
/Users/samkellett/Software/ray/yard_ext.rb:19:in `<top (required)>': uninitialized constant YARD::Parser::CParser (NameError)
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/command.rb:69:in `load'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/command.rb:69:in `load_script'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/command.rb:27:in `block in common_options'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/optparse.rb:1395:in `call'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/optparse.rb:1395:in `block in parse_in_order'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/optparse.rb:1351:in `catch'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/optparse.rb:1351:in `parse_in_order'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/optparse.rb:1345:in `order!'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/optparse.rb:1437:in `permute!'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/optparse.rb:1459:in `parse!'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/command.rb:55:in `parse_options'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/yardoc.rb:506:in `optparse'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/yardopts_command.rb:96:in `parse_yardopts'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/yardopts_command.rb:40:in `parse_arguments'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/yardoc.rb:276:in `parse_arguments'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/yardoc.rb:241:in `run'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/command.rb:13:in `run'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/command_parser.rb:71:in `run'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/lib/yard/cli/command_parser.rb:53:in `run'
    from /Library/Ruby/Gems/2.0.0/gems/yard-0.8.7.6/bin/yard:12:in `<top (required)>'
    from /usr/bin/yard:23:in `load'

The yard I'm using is the one installed via: gem install yard