Hi, On AIX 7.3.1, GNU sed fails to compile: CC sed/sed-sed.o ../sed/sed.c:20:10: fatal error: getopt.h: No such file or directory 20 | #include | ^~~~~~~~~~ compilation terminated. make: 1254-004 The error code from the last command is 1. Likewise on native Windows, with the MSVC compiler: sed\sed.c(20): fatal error C1083: Cannot open include file: 'getopt.h': No such file or directory make[2]: *** [Makefile:6034: sed/sed-sed.obj] Error 2 This patch fixes it, by using the Gnulib module 'getopt-gnu', as documented in https://www.gnu.org/software/gnulib/manual/html_node/getopt_002eh.html