That's a simple case, I've seen much worse because of endianess and different archs have different conventions for whether char is signed or unsigned by default

That's a simple case, I've seen much worse because of endianess and different archs have different conventions for whether char is signed or unsigned by default (common these days with arm/X86). Any C programmer who's coded for X86 and ARM will know what the rules are and how not to break them (I'd like to hope, anyway).