PVS-Studio warning V666 for ITK

bool MetaScene::
Read(const char *_headerName)
{
  ....
  else if(!strncmp(objectType.c_str(),"Image",5) ||
  ....
  else if(!strncmp(objectType.c_str(),"Blob",4) ||
  ....
  else if(!strncmp(objectType.c_str(),"Landmark",8) ||
  ....
  else if(!strncmp(objectType.c_str(),"Surface",5) ||
  ....
}

This suspicious code was found in ITK project by PVS-Studio static code analyzer.
Warning message is:
V666 Consider inspecting third argument of the function 'strncmp'. It is possible that the value does not correspond with the length of a string which was passed with the second argument. metascene.cxx 313

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/