[This may be of interest to people on xemacs-beta too] Hrvoje Niksic <hniksic(a)srce.hr&gt; writes: Hrvoje, there is a part of configure.in you seem to have missed: -*) dnl If FOO is a boolean argument, --FOO is equivalent to dnl --FOO=yes. Otherwise, the value comes from the next dnl argument - see below. opt=`echo '' $arg | sed -e 's:^ ::' -e 's:^-*\(.*\)$:\1:'` val="yes" valomitted=yes Boolean variables in configure.in are actually tristate, "yes", "no" or empty. Empty means that the user did not specify anything in the configure command line. Specifying "--with-xxx" without a parameter will give a "yes" in $with_xxx. Specifying "--without-xxx" gives "no" in $with_xxx. -test -z "$with_offix" && with_offix=yes +test -z "$with_offix" && with_offix=no This has to be interpreted as changing "if the user didn't specify anything, default to yes" to "if the user didn't specify anything, default to no". Exactly the effect intended. OG.