PVS-Studio warning V547 for QuickThread

int numa_preferred(void)
{
  unsigned char NUMA_NodeNumber = numa_available();
  if(NUMA_NodeNumber >= 0)
    return NUMA_NodeNumber;
  return 0;
}

This suspicious code was found in QuickThread project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'NUMA_NodeNumber >= 0' is always true. Unsigned type value is always >= 0. quickthreadnuma.cpp 101

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/