PVS-Studio warning V579 for Chromium

int  AffixMgr::parse_convtable(..., const char * keyword)
{
  ...
  if (strncmp(piece, keyword, sizeof(keyword)) != 0) {
  ...
}

This suspicious code was found in Chromium project by PVS-Studio static code analyzer.
Warning message is:
V579 The strncmp function receives the pointer and its size as arguments. It is possibly a mistake. Inspect the third argument. hunspell affixmgr.cxx 3545

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/