PVS-Studio warning V547 for Source SDK

static void AddNodeToBounds(....)
{
  ....
  unsigned int firstedge = dfaces[face].firstedge;
  Assert( firstedge >= 0 );
  ....
}

This suspicious code was found in Source SDK project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'firstedge >= 0' is always true. Unsigned type value is always >= 0. Vbsp writebsp.cpp 1428

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