Composer breaks exisiting autoload in Codeigniter

[eluser]coderego[/eluser]
I was using Codeigniter to do autoloading for some core classes using the method described here:

Code:

http://philsturgeon.co.uk/blog/2010/02/CodeIgniter-Base-Classes-Keeping-it-DRY

function __autoload($class)
{
if(strpos($class, 'CI_') !== 0)
{
  @include_once( APPPATH . 'core/'. $class . EXT );
}
}

However, once I installed composer (in order to use Eloquent), this funcitonality no longer works. Any ideas?

Thanks!