continue;
// History based pruning
- if ( depth <= 3 * ONE_PLY
+ if ( depth <= 4 * ONE_PLY
+ && move != ss->killers[0]
&& thisThread->history[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO
&& cmh[pos.moved_piece(move)][to_sq(move)] < VALUE_ZERO)
continue;