PVS-Studio warning V557 for Doom3

static bool R_ClipLineToLight(..., const idPlane frustum[4], ...)
{
  ...
  for ( j = 0 ; j < 6 ; j++ ) {
    d1 = frustum[j].Distance( p1 );
    d2 = frustum[j].Distance( p2 );
    ...
  }
  ...
}

This suspicious code was found in Doom3 project by PVS-Studio static code analyzer.
Warning message is:
V557 Array overrun is possible. The value of 'j' index could reach 5. DoomDLL tr_stencilshadow.cpp 551

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/