version 20190131 has been released and fixes several issues: https://github.com/kirei/fpdns/releases/tag/20190131 fixes this issue with fpdns-0.10.0_pre20130404-r1: Use of uninitialized value $_ in pattern match (m//) at /usr/lib64/perl5/vendor_perl/5.26.2/Net/DNS/Resolver/Base.pm line 986. Use of uninitialized value $_ in pattern match (m//) at /usr/lib64/perl5/vendor_perl/5.26.2/Net/DNS/Resolver/Base.pm line 987. Use of uninitialized value $_ in pattern match (m//) at /usr/lib64/perl5/vendor_perl/5.26.2/Net/DNS/Resolver/Base.pm line 988.