sed -i is a gnu extension and is not present in OpenBSD's sed. thunar hardcodes its use in thunar/Makefile.am: thunar/Makefile.am: && sed -i -e 's/org_freedesktop_thumbnails_Thumbnailer1/thunar_thumbnailer_proxy/g' \ thunar/Makefile.am: && sed -i -e 's/org_freedesktop_thumbnails_Cache1/thunar_thumbnail_cache_proxy/g' \ configure should check for SED program (so that we can override it with SED=/usr/local/bin/gsed on OpenBSD) and use $(SED) in Makefile.am instead. A way to check for it is : dnl AC_PROG_SED is only avaliable in recent autoconf versions. dnl Use AC_CHECK_PROG instead if AC_PROG_SED is not present. ifdef([AC_PROG_SED], [AC_PROG_SED], [AC_CHECK_PROG(SED, sed, sed)]) (taken from http://svn.apache.org/repos/asf/apr/apr/trunk/configure.in) AC_PROG_SED macro is available since autoconf 2.62.
Fixed in 7c194fa.