Udo van den Heuvel wrote: [...] >> cd . && autoconf >> configure.in:8: /usr/bin/m4: Warning: sub-expression 1 not present [...] > Looks like an m4 bug: > http://www.mail-archive.com/bug-m4@gnu.org/msg01831.html So I updated m4 to 1.4.8 and tor builds OK now. Udo