ftp://ftp.netbsd.org/pub/NetBSD/packages/2.0/alpha/All/png-1.2.8.tgz

-rw-rw-r--   1 1115  netbsd    283759 Feb  6 22:01 png-1.2.8.tgz

MD5 (/tmp/png-1.2.8.tgz) = b168b2e1bed5f1b867067f7eabdb51f3

sopwith # pkg_add  png-1.2.8.tgz 
tar: Invalid header, starting valid header search.
tar: Header checksum 13142 does not match 13124
tar: Header checksum 12103 does not match 11673
gzip: invalid compressed data--crc error
pkg_add: extract of /tmp/./png-1.2.8.tgz failed
pkg_add: unable to extract `/tmp/./png-1.2.8.tgz'!
pkg_add: 1 package addition failed
sopwith # 

sopwith gunzip < png-1.2.8.tgz > foo
gunzip: invalid compressed data--crc error