if [[ $pkgver == "2.3.1" && $pkgrel == 5 ]]; then
    # Thank you for the mirror. (Since it matches the existing checksums, it's safe.)
    source[0]='http://www.mirrorservice.org/sites/ftp.netbsd.org/pub/pkgsrc/distfiles/libsieve-2.3.1.tar.gz'
fi