Reported by Alberto Sartori:
I just tried to compile it with gcc-10.3 and clang-12 on a linux machine running gentoo. However, it says multiple definitions of several symbols.
Indeed. The Apple clang (13.0.0) succeeds, whereas GCC 11.2.0 reports multiple definitions of extra_scraps, current_sector, prev_sector, blockBuff.
Fixed in release 1.61.