This is too specific and will not work for non-standard install locations. You probably want to use something like this:

```ruby
tmux_root = File.realpath(`brew --prefix tmux`.chomp)
tmux_version = tmux_root[%r{/([^/]+)$}, 1].to_f
```

Technically the `.to_f` is also not going to work all the time, either, but for our specific version check it should be fine. This illustrates the problem:

```ruby
> Gem::Version.new('0.3.4') > Gem::Version.new('0.13')
=> false
> '0.3.4' > '0.13'
=> true
```