PVS-Studio warning V547 for Word11a

void GetNameElk(elk, stOut)
ELK elk;
unsigned char *stOut;
{
  unsigned char *stElk = &rgchElkNames[mpelkichName[elk]];
  unsigned cch = stElk[0] + 1;

  while (--cch >= 0)
    *stOut++ = *stElk++;
}

This suspicious code was found in Word11a project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression '-- cch >= 0' is always true. Unsigned type value is always >= 0. mergeelx.c 1188

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