Dear libtool maintenance team! Please note that m4/libtool.m4 file (starting from 2.4.2.418) has incorrect string comparition that leads to wrong behaviour related to default library paths. See m4/libtool.m4 at string 7559 ( http://git.savannah.gnu.org/cgit/libtool.git/tree/m4/libtool.m4#n7559) # Some compilers place space between "-{L,R}" and the path. # Remove the space. if test x-L = "$p" || test x-R = "$p"; then prev=$p continue Both tests are being performed without 'x' in right parts (i.e. "$p" instead of "x$p"), what makes them always false. Hope this information is helpful. Best regards, Igor.