if (!pos.capture_or_promotion(ttMove))
update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
- // Extra penalty for a quiet TT move in previous ply when it gets refuted
- if ((ss-1)->moveCount == 1 && !pos.captured_piece())
- update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+ // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
+ if ( (ss-1)->moveCount == 1
+ || ((ss-1)->currentMove == (ss-1)->killers[0] && (ss-1)->killers[0]))
+ if (!pos.captured_piece())
+ update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
}
// Penalty for a quiet ttMove that fails low
else if (!pos.capture_or_promotion(ttMove))