- my $millisecond = 0;
- my ($hour, $minute, $second) = split m/:/, $time_str;
- ($second, $millisecond) = split quotemeta($num_separator), $second, 2;
+ my ($hour, $minute, $second) = split m/:/, ($time_str || '');
+ $second ||= '0';
+
+ ($second, my $millisecond) = split quotemeta($num_separator), $second, 2;
+ $_ ||= 0 for ($hour, $minute, $millisecond);
+