PVS-Studio warning V547 for Miranda IM

typedef UINT_PTR WPARAM;

static int id2pos(int id)
{
  int i;
  if (FramesSysNotStarted) return -1;
  for (i=0;i<nFramescount;i++)
  {
    if (Frames[i].id==id) return(i);
  }
  return(-1);
}

INT_PTR CLUIFrameSetFloat(WPARAM wParam,LPARAM lParam)
{
  ...
  wParam=id2pos(wParam);
  if(wParam>=0&&(int)wParam<nFramescount)
    if (Frames[wParam].floating)
  ...
}

This suspicious code was found in Miranda IM project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'wParam >= 0' is always true. Unsigned type value is always >= 0.  clist_mw  cluiframes.c  3140

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