}
size_t raw_fd_ostream::preferred_buffer_size() const {
-#if !defined(_MSC_VER) && !defined(__MINGW32__) // Windows has no st_blksize.
+#if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(_MINIX)
+ // Windows and Minix have no st_blksize.
assert(FD >= 0 && "File not yet open!");
struct stat statbuf;
if (fstat(FD, &statbuf) != 0)