- # assign the default file.
- $disk->{FILENAME} = $disk->{DEF_FN}
- if !defined ($disk->{FILENAME}) && -e $disk->{DEF_FN};
+ # try to assign a default file name.
+ if (!defined ($disk->{FILENAME})) {
+ for my $try_fn ($disk->{DEF_FN}, "build/" . $disk->{DEF_FN}) {
+ $disk->{FILENAME} = $try_fn, last
+ if -e $try_fn;
+ }
+ }