The new 64-Bit ARM architecture (official abbreviation Aarch64) is coming with strong Linux support. This talk details typical changes that applications need to build and run on Aarch64. Aarch64 leaves behind many of the idiosyncrasies of 32-Bit ARM for a new clean start, thus making porting easier in many cases. GCC and Autoconf provide tools to make code adapt using the "detect feature, not platform" philosophy. In this talk we dive into both Aarch64 specific changes needed and general portability tips. Many of instructions provided should be helpful for porting GNU/Linux applications to any new architecture.