Regexp errors on OpenBSD

I installed scsh 0.6.7 on OpenBSD 3.9, but I'm having problems with
regular expressions:

    $ ( echo '(regexp-search (rx printing) "foo")'; echo ',exit' ) | ./go | cat -v
    Welcome to scsh 0.6.7 (R6RS)
    Type ,? for help.
    > 
    Error: Posix regexp ([^M-2M-3M-9M-<M-=M->^A-^H^N-^_^?-M-^_]) : invalid character range
           #{Regexp}
    1>

(cat -v because the M-* and ^* sequences aren't ASCII characters and
aren't pasting properly otherwise.)

Any ideas what's up?  The same input to OpenBSD's scsh 0.6.2 package
runs without error.  I've tried using gdb to track down where the
error's originating, but after I hit the breakpoint at
posix_compile_regexp, trying to step forward at all immediately takes
me to the above error. :/