Hello, I try to build branch emacs-25 (commit f2819241bc93b641f13e1a04f3520fadb8ed53a8) on Windows 10. Following the instructions of file nt/INSTALL.W64, autogen.sh gives me : INCONNU@DESKTOP-RU9MU9H MINGW64 /c/emacs-git $ ./autogen.sh Checking whether you have the necessary tools... (Read INSTALL.REPO for more details on building Emacs) Checking for autoconf (need at least version 2.65)... ok Checking for automake (need at least version 1.11)... ok Your system has the required tools. Running 'autoreconf -fi -I m4' ... ' is already registered with AC_CONFIG_FILES. ../../lib/autoconf/status.m4:288: AC_CONFIG_FILES is expanded from... configure.ac:5374: the top level autom4te: /usr/bin/m4 failed with exit status: 1 aclocal-1.15: error: echo failed with exit status: 1 autoreconf: aclocal failed with exit status: 1 It says my system has the required tools but fails to build anyway. Also the error gives me litlle information about what went wrong. Thanks, Vincent