sub BEGIN {
    my ( $dir, $orig_dir );
    require File::Spec;
    if ( !( $dir = $ENV{MT_HOME} ) ) {
        if ( $0 =~ m!(.*([/\\]))! ) {
            $orig_dir = $dir = $1;
            my $slash = $2;
            $dir =~ s!(?:[/\\]|^)(?:plugins[/\\].*|tools[/\\])$!$slash!;
            $dir = '' if ( $dir =~ m!^\.?[\\/]$! );
        }
        elsif ( $] >= 5.006 ) {

         # MT_DIR/lib/MT/Bootstrap.pm -> MT_DIR/lib/MT -> MT_DIR/lib -> MT_DIR
            require File::Basename;
            $dir = File::Basename::dirname(
                File::Basename::dirname(
                    File::Basename::dirname( File::Spec->rel2abs(__FILE__) )
                )
            );
        }
        unless ($dir) {
            $orig_dir = $dir = $ENV{PWD} || '.';
            $dir =~ s!(?:[/\\]|^)(?:plugins[/\\].*|tools[/\\]?)$!!;
        }
        $ENV{MT_HOME} = $dir;
    }
    unshift @INC, File::Spec->catdir( $dir,      'extlib' );
    unshift @INC, File::Spec->catdir( $orig_dir, 'lib' )
        if $orig_dir && ( $orig_dir ne $dir );
}