WordPress to Jekyll script throwing error

I’ve been wrestling with this problem for a day or so and cannot figure out what’s going on. I’m trying to run a script to import my WordPress .sql into Jekyll and convert everything to markdown. But every time I run the script (on both Mac and Ubuntu) I’m getting an error. I’m at a loss of what to do. Here’s my terminal output and gem list:

jason@ubuntu:~$ ruby -r './wordpress.rb' -e 'Jekyll::WordPress.process( "#{ENV["DB"]}", "#{ENV["USER"]}", "#{ENV["PASS"]}")'
/usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require': LoadError: no such file to load -- mysql (Sequel::AdapterNotFound)
    from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `require'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/adapters/mysql.rb:4
    from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
    from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `k_require'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:249:in `tsk_require'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:72:in `check_requiring_thread'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:69:in `synchronize'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:69:in `check_requiring_thread'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:249:in `tsk_require'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/database/connecting.rb:25:in `adapter_class'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/database/connecting.rb:63:in `connect'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:119:in `connect'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:282:in `adapter_method'
    from /var/lib/gems/1.8/gems/sequel-3.22.0/lib/sequel/core.rb:289:in `mysql'
    from ./wordpress.rb:35:in `process'
    from -e:1
jason@ubuntu:~$ gem list

*** LOCAL GEMS ***

classifier (1.3.3)
directory_watcher (1.4.0)
fast-stemmer (1.0.0)
jekyll (0.10.0)
liquid (2.2.2)
maruku (0.6.0)
sequel (3.22.0)
syntax (1.0.0)

I’m using Paul Stamatiou’s adapted script. Thanks ahead of time for any suggestions!