Hello, what is needed to force bjam to build zlib? Is the zlib.h enough? Also is there a way to make bjam fail compiling if I set "NO_ZLIB=0" and it does not find the zlib.h / source? It is really inconvenient that bjam silently switches off zlib without any error or warning why zlib is not being build. My commands are: ./bootstrap.sh --without-libraries=python --prefix=/home/simon/code/cfs/release_mingw_openblas/cfsdeps/boost/install --with-toolset=gcc --without-libraries=context --without-libraries=coroutine target-os=windows architecture=x86 address-model=64 release and ./b2 target-os=windows architecture=x86 address-model=64 release --user-config=user-config.jam toolset=gcc-mingw -s ZLIB_BINARY=\"/home/simon/code/cfs/release_mingw_openblas/lib64/MINGW_X86_64/libzlibstatic.a\" -s ZLIB_INCLUDE=\"/home/simon/code/cfs/release_mingw_openblas/include\" -s NO_ZLIB=0 threading=multi install (this is cross compiling, but I have the same problem building for Linux) Regards, Simon