https://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-handbook/versions.html#versions-13 sysctl kern.osreldate /usr/src/sys/sys/param.h #define __FreeBSD_version 1300102 Modify the /usr/src/sys/sys/param.h __FreeBSD_version to the value get by sysctl kern.osreldate in the OS.