PVS-Studio warning V576 for ReactOS

int WINAPI WinMain(....)
{
  LPWSTR *argvW = NULL;
  ....
  fprintf(stderr,
    "Unknown option \"%c\" in Repair mode\n", argvW[i][j]);
  ....
}

This suspicious code was found in ReactOS project by PVS-Studio static code analyzer.
Warning message is:
V576 Incorrect format. Consider checking the third actual argument of the 'fprintf' function. The char type argument is expected. msiexec.c 655

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/