diff --git a/Userland/Libraries/LibChess/Chess.h b/Userland/Libraries/LibChess/Chess.h
index 5a75a8c5696..2a25972484c 100644
--- a/Userland/Libraries/LibChess/Chess.h
+++ b/Userland/Libraries/LibChess/Chess.h
@@ -278,7 +278,7 @@ void Board::generate_moves(Callback callback, Color color) const
 
 template<>
 struct AK::Traits<Chess::Piece> : public GenericTraits<Chess::Piece> {
-    static unsigned hash(const Chess::Piece& piece)
+    static unsigned hash(Chess::Piece const& piece)
     {
         return pair_int_hash(static_cast<u32>(piece.color), static_cast<u32>(piece.type));
     }
@@ -286,7 +286,7 @@ struct AK::Traits<Chess::Piece> : public GenericTraits<Chess::Piece> {
 
 template<>
 struct AK::Traits<Chess::Board> : public GenericTraits<Chess::Board> {
-    static unsigned hash(const Chess::Board chess)
+    static unsigned hash(Chess::Board const& chess)
     {
         unsigned hash = 0;
         hash = pair_int_hash(hash, static_cast<u32>(chess.m_white_can_castle_queenside));
@@ -294,8 +294,6 @@ struct AK::Traits<Chess::Board> : public GenericTraits<Chess::Board> {
         hash = pair_int_hash(hash, static_cast<u32>(chess.m_black_can_castle_queenside));
         hash = pair_int_hash(hash, static_cast<u32>(chess.m_black_can_castle_kingside));
 
-        hash = pair_int_hash(hash, static_cast<u32>(chess.m_black_can_castle_kingside));
-
         Chess::Square::for_each([&](Chess::Square sq) {
             hash = pair_int_hash(hash, Traits<Chess::Piece>::hash(chess.get_piece(sq)));
             return IterationDecision::Continue;