Can't use string as a subroutine ref while "strict refs"

[Sara]

use strict;
use warnings;
use CGI;

my $q = new CGI;

my $do = $q->param('do') || 'main'';

if ($do) {
&$do;
}

sub main {
blah blah
}
=========================================
Trying to call the subroutine main from variable $do but I am gettin' error:
Can't use string ("main") as a subroutine ref while "strict refs.
But somehow I don't want to remove the 'use Strict;'

Any way out?

Sara.