PVS-Studio warning V610 for Virtualdub

void AVIVideoGIFOutputStream::write(....) {
{
  ....
  for(int i=0; i<palsize; ++i)
    dict[i].mPrevAndLastChar = (-1 << 16) + i;
  ....
}

This suspicious code was found in Virtualdub project by PVS-Studio static code analyzer.
Warning message is:
V610 Undefined behavior. Check the shift operator '<<. The left operand '-1' is negative. VirtualDub avioutputgif.cpp 702

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/