sub prettyprint_pv {
my ($pos, @pvs) = @_;
- my $cachekey = $pos->{'fen'} . join('', @pvs);
+ my $cachekey = $pos->fen() . join('', @pvs);
if (exists($pos->{'prettyprint_cache'}{$cachekey})) {
return @{$pos->{'prettyprint_cache'}{$cachekey}};
} else {