https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70464
--- Comment #3 from ge...@schorsch-tech.de --- I tried on the Raspberry pi 64 bit with the "C only gcc": Pi_3 64_bit ~ # cat main.c #include <stdio.h> #include <stdint.h> int main(int argc, char** argv) { printf("sizeof int64_t=%d\n",sizeof(int64_t)); return 0; } Pi_3 64_bit ~ # gcc main.c Pi_3 64_bit ~ # ./a.out sizeof int64_t=8 Pi_3 64_bit ~ # gcc --version gcc (GCC) 5.3.0 Copyright (C) 2015 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.