Hello, I'm trying to build boost 1.80 on windows 10 with the icu provided with msys2 (my goal in particular is that boost locale will build using my installed version of icu). My build platform is msys2 with mingw-w64 / gcc 12.2. By launching pacman -Q on the msys2-msys shell I have seen that I have icu 71.1-2 : (...) glib2 2.72.2-2 gmp 6.2.1-2 gnupg 2.2.36-1 grep 1~3.0-3 gzip 1.12-2 heimdal-libs 7.7.0-3 icu 71.1-2 inetutils 1.9.4-5 info 6.8-4 less 590-2 (...) on my system I have msys2 installed in the following folder C:programsmsys64 and in C:programsmsys64mingw64 there are the following folders : bin etc include lib libexec sbin share ssl var x86_64-w64-mingw32 in the lib folder I have found that there are lib files like libicuio.a, libicudt.a and libicutest.a . I extracted boost and then I've given the usual sequence of commands from the normal cmd shell of windows : for creating b2 : bootstrap.bat gcc for the actual build of boost, I've made the following attempts : b2 --toolset=gcc address-model=64 -sICU_PATH=C:programsmsys64mingw64 b2 --toolset=gcc address-model=64 include=C:programsmsys64mingw64include library-path=C:programsmsys64mingw64lib b2 --toolset=gcc address-model=64 -sICU_PATH=C:programsmsys64mingw64 include=C:programsmsys64mingw64include library-path=C:programsmsys64mingw64lib but none of these works : the build process always writes in its initial phase : (...) has_lzma_cputhreads builds : yes [2] cxx11_decltype : yes [2] cxx11_basic_alignas : yes [2] iconv (libc) : no [2] iconv (separate) : yes [2] icu : no [2] icu (lib64) : no [2] native atomic int32 supported : yes [2] has message compiler : no [2] native syslog supported : no [2] (...) what am I supposed to do to let b2 see the ICU lib files that I have in my msys2 distribution ? Thanks, Marco Voucher MISE per P.IVA e PMI: fino a 2500€ per la Banda Ultralarga. https://casa.tiscali.it/promo/?u=https://promozioni.tiscali.it/voucher_business/?r=TS00000A00025&dm=link&p=tiscali&utm_source=tiscali&utm_medium=link&utm_campaign=voucherbusiness&wt_np=tiscali.link.footermail.voucherbusiness.btb..