https://issues.dlang.org/show_bug.cgi?id=13241 --- Comment #8 from Sobirari Muhomori <dfj1esp02 at sneakemail.com> --- My guess is that on linux and ms fwrite detects line break and flushes the buffer, while snn fwrite writes in binary mode. It can also manifest in not translating \n to \r\n on windows. --