Package: gcc-multilib Version: 4:6.3.0-4 The package gcc-multilib conflicts with any GCC cross toolchains (for example "gcc-aarch64-linux-gnu"). As far as I understood it, it is not possible to build 32-bit binaries on a 64-bit system (using -m32 flag) when a GCC cross toolchain is installed. I am using Debian Stretch (stable).