diff --git a/engine/src/chessmove.rs b/engine/src/chessmove.rs
index 57c3d3a..0675ded 100644
--- a/engine/src/chessmove.rs
+++ b/engine/src/chessmove.rs
@@ -10,6 +10,5 @@ pub struct ChessMove {
   pub to_square: BoardSquare,
   pub rook_from: BoardSquare,
   pub rook_to: BoardSquare,
-  pub is_promotion: bool,
-  pub promotion_piece: PieceType
+  pub promotion_piece: Option<PieceType>
 }
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