When cross compiling inteltool with musl-libc the <sys/io.h> header is not included due to this test in inteltool.h: #if defined(__GLIBC__) #include <sys/io.h> #endif Unfortunately I'm not sure what the right test is here, since the musl libc team is opposed to having a __MUSL__ define: http://openwall.com/lists/musl/2013/03/29/13 -- Trammell