overviewer/Minecraft-Overviewer — comment on commit 868256b538a2c7ae8f4aebb5c27b2380568589f7
File: overviewer_core/src/composite.c line 65
By contre:

Since this just got reverted, if someone tries to fix this later, by changing these to unsigned int, it is possible that xsize and ysize could become VERY large positive numbers instead of negative numbers because of the -= operation on lines 90 and 91. This will only happen if sx and sy are larger than xsize and ysize. I'm not sure what the proper fix would be.