PVS-Studio warning V557 for dumb

struct IT_SAMPLE
{
  ...
  unsigned char filename[14];
  ...
};

static int it_riff_dsmf_process_sample(
  IT_SAMPLE * sample, const unsigned char * data, int len)
{
  int flags;
  memcpy( sample->filename, data, 13 );
  sample->filename[ 14 ] = 0;
  ...
}

This is what should have been written here: sample->filename[ 13 ] = 0;

This suspicious code was found in dumb project by PVS-Studio static code analyzer.
Warning message is:
V557 Array overrun is possible. The '14' index is pointing beyond array bound. dumb_static readdsmf.c 34

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/