PVS-Studio warning V547 for amtsdk

int HECIWin::_doIoctl(....)
{
  DWORD bytesRead = 0;
  ...
  if (bytesRead < 0) {
    Deinit();
  }
  ...
}

This suspicious code was found in amtsdk project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'bytesRead < 0' is always false. Unsigned type value is never < 0. ZTCLocalAgent heciwin.cpp 357

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/