`rspec --configure autotest` throws "uninitialized constant Class::FileUtils"

I'm trying to setup autotest with RSpec. Never had a problem before, but when I run rspec --configure autotest, I get the following error/trace:

Autotest loads RSpec's Autotest subclass when there is a .rspec file in the project's root directory.
/Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/backward_compatibility.rb:20:in `const_missing': uninitialized constant Class::FileUtils (NameError)
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/command_line_configuration.rb:38:in `create_dot_rspec_file'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/command_line_configuration.rb:29:in `generate'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/command_line_configuration.rb:12:in `run'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/option_parser.rb:101:in `block (2 levels) in parser'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1277:in `call'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1277:in `block in parse_in_order'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1264:in `catch'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1264:in `parse_in_order'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1258:in `order!'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1349:in `permute!'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1370:in `parse!'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/option_parser.rb:18:in `parse!'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/option_parser.rb:4:in `parse!'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/configuration_options.rb:88:in `command_line_options'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/configuration_options.rb:122:in `custom_options_file'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/configuration_options.rb:65:in `parse_options'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/runner.rb:41:in `run'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/ge开发者_如何学JAVAms/rspec-core-2.5.1/lib/rspec/core/runner.rb:10:in `block in autorun'

Simply running rspec runs just fine, and running autotest runs fine as well, but only loads Cucumber features. Also, require 'fileutils' returns true in irb. Any ideas?

---

I'm not sure why, and it seems like this can't be the correct solution, but deleting and recreating the .rspec file solved the problem.