Starting with version 3.9.5 platform.win32* functions have been re-written and consume STDIN. The bug comes down to running 'ver', 'command /c ver', 'cmd /c ver' in platform._syscmd_ver() via subprocess.check_output(). The following code demonstrate the problem: Python\396\python -c "import platform as p, sys;print(sys.stdin.tell());p.win32_ver();print(sys.stdin.tell())" < file 0 8000 All functions dependent on platform._syscmd_ver(), including platform.uname(), consume STDIN. This behavior breaks all the scripts on Windows platform that have the calls mentioned above and use the following invocation: python script.py < file