PVS-Studio warning V579 for FAR

struct TreeItem
{
  int *Last;
  size_t LastCount;
  ...
  void Clear()
  {
    strName.Clear();
    memset(Last,0,sizeof(Last));
    Depth=0;
  }
};

This is what should have been written here: memset(Last,0,LastCount*sizeof(int));

This suspicious code was found in FAR project by PVS-Studio static code analyzer.
Warning message is:
V579 The memset function receives the pointer and its size as arguments. It is possibly a mistake. Inspect the third argument. far treelist.hpp 66

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/