When running mingw-64-install.exe, you have to choose the x86_64 architecture on the settings screen. With this architecture, 64-bit is also the default target. If you run g++ -v, you should get something like: C:\>g++ -v Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=C:/Program\ Files/mingw-w64/x86_64-5.3.0-posix-seh-rt_v4-rev0/mingw64/bin/../libexec/gcc/x86_64-w64-mingw32/5.3.0/lto-wrapper.exe Target: x86_64-w64-mingw32 Configured with: ../../../src/gcc-5.3.0/configure –host=x86_64-w64-mingw32 –build=x86_64-w64-mingw32 –target=x86_64-w64-mingw32 –prefix=/mingw64 –with-sysroot=/c/mingw530/x86_64-530-posix-seh-rt_v4-rev0/mingw64 –with-gxx-include-dir=/mingw64/x86_64-w64-mingw32/include/c++ –enable-shared –enable-static –disable-multilib … Read more