Minor nitpick, but this should probably be more specific about when you need to. In fact, we could make the entire thing print only when necessary (because this isn't necessary for /usr/local prefixes, right?):

```ruby
def caveats
  s = ''
  if HOMEBREW_PREFIX.to_s != '/usr/local'
    s << <<-EOS.undent
      You must add the following line to your .bashrc or equivalent:
        export NEKOPATH="#{HOMEBREW_PREFIX}/lib/neko"
      EOS
  end

  s
end
```