fix: correctly update occupancy in en passant

1 files changed, 3 insertions, 1 deletions

diff --git a/src/board/mod.rs b/src/board/mod.rs
index c889257..a5803ac 100644
--- a/src/board/mod.rs
+++ b/src/board/mod.rs
@@ -536,7 +536,9 @@ impl Board {
             let captured_square = Square::from_coords(mov.source.rank(), mov.target.file());
             captured_piece = match self.piece_by_square(captured_square) {
                 Some(pawn_type) => {
-                    self.pieces[pawn_type as usize] ^= captured_square.to_bitboard();
+                    let captured_bb = captured_square.to_bitboard();
+                    self.pieces[pawn_type as usize] ^= captured_bb;
+                    self.occupancy                  ^= captured_bb;
                     self.hash ^= self.zobrist_seed[pawn_type as usize* 64 + captured_square as usize];
                     Some(pawn_type)
                 },