PVS-Studio warning V547 for Miranda IM

extern DWORD nMessagesCount;

static void MirabilisImport(HWND hdlgProgressWnd)
{
  ...
  nGroupsCount = ImportGroups();
  if (nGroupsCount < 0) {
    AddMessage( LPGEN("Group import was not completed."));
    nGroupsCount = 0;
  }
  ...
}

This suspicious code was found in Miranda IM project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'nGroupsCount < 0' is always false. Unsigned type value is never < 0.  import  mirabilis.c  1416

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