Works on 5.8+:

use v5.8.8;
[download]

Works on 5.6+:

use 5.008_008;
[download]

Works on 5.0+:

BEGIN {
   $] >= 5.008_008
      or die("Need half-decent Unicode support. "
         .   "Please use Perl 5.8.8 or higher\n");
}
[download]

I could be wrong as to when each started working.