The fix for the issue your raised in now in MKCL's git repository and will be part of MKCL 1.1.9, to be released in a few days.

In the meantime if you need immediate access to it you could clone the MKCL git repository using this command:

git clone git://common-lisp.net/projects/mkcl/mkcl.git

and rebuild MKCL from it (the usual "configure"; make install sequence).

Thank you again for your bug report.