PVS-Studio warning V557 for TPP

int main(int argc, char **argv) {
  ...
  char salt[3];
  ...
  salt[0] = (argc>2)?(argv[1][0]):rndChar[rand() % 64];
  salt[1] = (argc>2)?(argv[1][1]):rndChar[rand() % 64];
  salt[3] = 0;
  ...
}

This is what should have been written here: salt[2] = 0;

This suspicious code was found in TPP project by PVS-Studio static code analyzer.
Warning message is:
V557 Array overrun is possible. The '3' index is pointing beyond array bound. crypt crypt.cxx 567

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/