Dynamic ELF patching on BSD with libmonkey-Collection of common programming errors

I played a little bit with nice library called libmonkey which gives nice interface for dynamic ELF patching on Linux. However, I’m trying to run it on FreeBSD; compilation passed, but I’m getting core dump in runtime (gdb is pointing header offset calculation code).

I’m not familiar with ELF, but aren’t headers should be the same on linux and freebsd?

Anyone have idea what is happening?

Thanks