PVS-Studio warning V501 for Audacity

sampleCount VoiceKey::OnBackward (....) {
  ...
  int atrend = sgn(buffer[samplesleft - 2]-
                   buffer[samplesleft - 1]);
  int ztrend = sgn(buffer[samplesleft - WindowSizeInt-2]-
                   buffer[samplesleft - WindowSizeInt-2]);
  ...
}

A Copy-Paste error. In the last line 1 should be subtracted instead of 2.

This suspicious code was found in Audacity project by PVS-Studio static code analyzer.
Warning message is:
V501 There are identical sub-expressions to the left and to the right of the '-' operator. Audacity voicekey.cpp 304

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/