https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70009
James Greenhalgh <jgreenhalgh at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target|powerpc*-*-*, aarch64-*-* |powerpc*-*-*, aarch64-*-*, | |arm*-*-* Last reconfirmed|2016-02-29 00:00:00 |2016-3-7 CC| |jgreenhalgh at gcc dot gnu.org --- Comment #5 from James Greenhalgh <jgreenhalgh at gcc dot gnu.org> --- Also failing on arm/aarch64 (so good further evidence of signed vs. unsigned char). Forcing the macro to use signed types clears the error for me on arm-none-linux-gnueabihf (though I don't know if this is correct).