Sass compile error - StalenessChecker:: Mutex (NameError)

Любые идеи об этой ошибке - sass compilejust fail - попробовали обновление gem - обновить систему и gem и удалить и переустановить сасс-камень

sudo sass --update --trace styles.scss overwrite styles.css
Password:
/Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/../lib/sass/../sass/plugin/staleness_checker.rb:27: uninitialized constant Sass::Plugin::StalenessChecker::Mutex (NameError)
    from /Library/Ruby/Site/1.8/rubygems/core_ext/kernel_require.rb:53:in `gem_original_require'
    from /Library/Ruby/Site/1.8/rubygems/core_ext/kernel_require.rb:53:in `require'
    from /Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/../lib/sass/../sass/plugin/compiler.rb:7
    from /Library/Ruby/Site/1.8/rubygems/core_ext/kernel_require.rb:53:in `gem_original_require'
    from /Library/Ruby/Site/1.8/rubygems/core_ext/kernel_require.rb:53:in `require'
    from /Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/../lib/sass/../sass/plugin.rb:4
    from /Library/Ruby/Site/1.8/rubygems/core_ext/kernel_require.rb:53:in `gem_original_require'
    from /Library/Ruby/Site/1.8/rubygems/core_ext/kernel_require.rb:53:in `require'
    from /Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/../lib/sass/../sass/exec.rb:381:in `watch_or_update'
    from /Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/../lib/sass/../sass/exec.rb:326:in `process_result'
    from /Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/../lib/sass/../sass/exec.rb:41:in `parse'
    from /Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/../lib/sass/../sass/exec.rb:21:in `parse!'
    from /Library/Ruby/Gems/1.8/gems/sass-3.2.11/bin/sass:9
    from /usr/bin/sass:23:in `load'
    from /usr/bin/sass:23