Hi, I'm not sure it's ok to post issue report about libc-test to this maillist, if it is not ok, please let me know. I downloaded the latest libc-test and run make, commit id of latest master is 287fe555a8279fab14e89e7cd64787d234a30ebf $ git clone git://repo.or.cz/libc-test $ cd libc-test $ CC=../install/bin/musl-gcc make I checked the output and see following error report: ../install/bin/musl-gcc -Isrc/common -Isrc/common -pipe -std=c99 -D_POSIX_C_SOURCE=200809L -Wall -Wno-unused-function -Wno-missing-braces -Wno-unused -Wno-overflow -Wno-unknown-pragmas -fno-builtin -frounding-math -Werror=implicit-function-declaration -Werror=implicit-int -Werror=pointer-sign -Werror=pointer-arith -g -D_FILE_OFFSET_BITS=64 -pedantic-errors -Werror -Wno-unused -D_XOPEN_SOURCE=700 -c -o src/api/unistd.o src/api/unistd.c 2>src/api/unistd.o.err || echo BUILDERROR src/api/unistd.o; cat src/api/unistd.o.err BUILDERROR src/api/unistd.o src/api/unistd.c: In function ¡®f¡¯: src/api/unistd.c:87:3: error: ¡®_CS_POSIX_V7_THREADS_CFLAGS¡¯ undeclared (first use in this function) 87 | C(_CS_POSIX_V7_THREADS_CFLAGS) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ I double checked and found it is due to lacking of "src/common/options.h", I found this file is not created successfully, and there is only src/common/options.h.in, that's make the build failed. Best Regards Wang Chen