Problems with OpenBSD 6.7

I have been running qmail without problems on OpenBSD, every version
from 2.3 through 6.6. After upgrading from 6.6 to 6.7 all of DJB's
software had to be recompiled. This had happened several times with
upgrades, so did not seem worrying. Upgraded a test server, recompiled
and everything seemed fine. Unfortunately, I did not test checkpassword.

*----------------------------------------------------------------------*
foo:~
{12} % /var/qmail/bin/qmail-popup foo.bar.perea.net /bin/checkpassword pwd
+OK <[email protected]>
user frodo
+OK
pass friend
-ERR aack, child crashed
foo:~
{13} % ls *.core
checkpassword.core
foo:~
{14} % 
*----------------------------------------------------------------------*

Life with qmail suggests looking for other password checking programs at
qmail.org, but that is no longer available.

I would greatly appreciate any suggestions.