diff --git a/src/board/game.rs b/src/board/game.rs
index 60a5fcf..50ed886 100644
--- a/src/board/game.rs
+++ b/src/board/game.rs
@@ -82,11 +82,8 @@ impl Game {
             }
             MoveType::EnPassant => {
                 board.move_piece(mv.src, mv.dst, piece_at_src);
-                let piece_at_capture = mailbox
-                    .piece_at(capture_square)
-                    .expect("Expected piece at: {capture_square}");
                 board.remove_opponent_piece(capture_square, PieceType::Pawn);
-                hash.update_en_passant(mv.src, mv.dst, piece_at_src, piece_at_capture, color);
+                hash.update_en_passant(mv.src, mv.dst, piece_at_src, color);
                 mailbox.set_piece_at(mv.dst, Some(piece_at_src));
                 mailbox.set_piece_at(capture_square, None);
             }
@@ -96,36 +93,21 @@ impl Game {
                     Color::White => Some(mv.src + 8),
                     Color::Black => Some(mv.src.saturating_sub(8)),
                 };
-                hash.update_double_push(
-                    mv.src,
-                    mv.dst,
-                    piece_at_src,
-                    color,
-                    board.state.en_passant_square,
-                );
+                hash.update_double_push(mv.src, mv.dst, color, board.state.en_passant_square);
                 mailbox.set_piece_at(mv.dst, Some(piece_at_src));
             }
             MoveType::Promotion(promote) => {
                 board.remove_own_piece(mv.src, piece_at_src);
                 board.promote_piece(mv.dst, promote);
-                hash.update_promotion(mv.src, mv.dst, piece_at_src, promote, color);
+                hash.update_promotion(mv.src, mv.dst, promote, color);
                 mailbox.set_piece_at(mv.dst, Some(promote.into_piece_type()));
             }
             MoveType::PromotionCapture(promote) => {
+                let piece_at_dst = piece_at_dst.expect("Expected piece at dst: {mv.dst}");
                 board.remove_own_piece(mv.src, piece_at_src);
-                board.remove_opponent_piece(
-                    mv.dst,
-                    piece_at_dst.expect("Expected piece at dst: {mv.dst}"),
-                );
+                board.remove_opponent_piece(mv.dst, piece_at_dst);
                 board.promote_piece(mv.dst, promote);
-                hash.update_promotion_capture(
-                    mv.src,
-                    mv.dst,
-                    piece_at_src,
-                    piece_at_dst.unwrap(),
-                    promote,
-                    color,
-                );
+                hash.update_promotion_capture(mv.src, mv.dst, piece_at_dst, promote, color);
                 mailbox.set_piece_at(mv.dst, Some(promote.into_piece_type()));
             }
             MoveType::Castle => {
diff --git a/src/board/zobrist.rs b/src/board/zobrist.rs
index edb6e61..6281137 100644
--- a/src/board/zobrist.rs
+++ b/src/board/zobrist.rs
@@ -161,42 +161,33 @@ impl ZobristHash {
         src: usize,
         dst: usize,
         piece_at_src: PieceType,
-        piece_at_capture: PieceType,
         color: Color,
     ) {
         let keys = zobrist_keys();
         self.hash ^= keys.piece_square_color[src][piece_at_src.idx()][color.idx()];
         self.hash ^= keys.piece_square_color[dst][piece_at_src.idx()][color.idx()];
-        self.hash ^= keys.piece_square_color[dst][piece_at_capture.idx()][color.opponent().idx()]
+        self.hash ^= keys.piece_square_color[dst][PieceType::Pawn.idx()][color.opponent().idx()]
     }
 
     pub fn update_double_push(
         &mut self,
         src: usize,
         dst: usize,
-        piece_at_src: PieceType,
         color: Color,
         new_en_passant_target: Option<usize>,
     ) {
         let keys = zobrist_keys();
-        self.hash ^= keys.piece_square_color[src][piece_at_src.idx()][color.idx()];
-        self.hash ^= keys.piece_square_color[dst][piece_at_src.idx()][color.idx()];
+        self.hash ^= keys.piece_square_color[src][PieceType::Pawn.idx()][color.idx()];
+        self.hash ^= keys.piece_square_color[dst][PieceType::Pawn.idx()][color.idx()];
 
         if let Some(new_en_passant) = new_en_passant_target {
             self.hash ^= keys.en_passant[square::to_file(new_en_passant)];
         }
     }
 
-    pub fn update_promotion(
-        &mut self,
-        src: usize,
-        dst: usize,
-        piece_at_src: PieceType,
-        promote: &Promote,
-        color: Color,
-    ) {
+    pub fn update_promotion(&mut self, src: usize, dst: usize, promote: &Promote, color: Color) {
         let keys = zobrist_keys();
-        self.hash ^= keys.piece_square_color[src][piece_at_src.idx()][color.idx()];
+        self.hash ^= keys.piece_square_color[src][PieceType::Pawn.idx()][color.idx()];
         self.hash ^= keys.piece_square_color[dst][promote.into_piece_type().idx()][color.idx()];
     }
 
@@ -204,13 +195,12 @@ impl ZobristHash {
         &mut self,
         src: usize,
         dst: usize,
-        piece_at_src: PieceType,
         piece_at_dst: PieceType,
         promote: &Promote,
         color: Color,
     ) {
         let keys = zobrist_keys();
-        self.hash ^= keys.piece_square_color[src][piece_at_src.idx()][color.idx()];
+        self.hash ^= keys.piece_square_color[src][PieceType::Pawn.idx()][color.idx()];
         self.hash ^= keys.piece_square_color[dst][piece_at_dst.idx()][color.opponent().idx()];
         self.hash ^= keys.piece_square_color[dst][promote.into_piece_type().idx()][color.idx()];
     }
@@ -239,10 +229,11 @@ mod tests {
         Ok(())
     }
 
+    //TODO: how to test
+    // test if an incremental position is the same as if it would be calculated from scratch
+
     #[test]
     fn test_update_hash() -> Result<(), String> {
-        //TODO: how to test
-        // test if an incremental position is the same as if it would be calculated from scratch
         Ok(())
     }
 }