PVS-Studio warning V579 for MAME

static const char *apr_magic =
  "ACT Apricot disk image\x1a\x04";

FLOPPY_IDENTIFY( apridisk_identify )
{
  UINT8 header[APR_HEADER_SIZE];

  /* get header */
  floppy_image_read(floppy, &header, 0, sizeof(header));

  /* look for the magic string */
  if (memcmp(header, apr_magic, sizeof(apr_magic)) == 0)
  ...
}

This suspicious code was found in MAME project by PVS-Studio static code analyzer.
Warning message is:
V579 The memcmp function receives the pointer and its size as arguments. It is possibly a mistake. Inspect the third argument.  apridisk.c 128

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/