Hello, After Windows ICC support was added to 'compile' script, similar could be done to 'libtool.m4'. Related patch added in attachment. It was tested for GMP builds using Windows ICC with layouts, and all builds tasks finished successfully. Additionally ensured, that it doesn't break builds using MSVC. CC: Peter Rosin, as Author of commit (http://git.savannah.gnu.org/cgit/libtool.git/commit/?id=1ac3ced59db72099c6049e05b3643042fd5a9ea4), CC: Jonathan L Peyton, as Author of commit (http://git.savannah.gnu.org/cgit/automake.git/commit/?id=c40e27e1c2a60f58e72e65d73d808f782d55494a), in case they'll be interested to make review aor join this discussion. Best, Alexander