diff --git a/cpp/src/board.cpp b/cpp/src/board.cpp
index a2d45da..6d9afa8 100644
--- a/cpp/src/board.cpp
+++ b/cpp/src/board.cpp
@@ -199,6 +199,24 @@ Board Board::make_move(Move move) const {
     } else {
         ret.en_passant_target = -1;
     }
+
+    // -- Handle castling (just move the rook over)
+    if (move.castle_side & KingSide) {
+        Coords c = Coords::from_index(move.source_square);
+        Coords rook_source{7, c.y};
+        int8_t old_rook = ret.squares[rook_source.to_index()];
+        ret.squares[rook_source.to_index()] = Piece::None;
+        Coords rook_dest{5, c.y};
+        ret.squares[rook_dest.to_index()] = old_rook;
+    } else if (move.castle_side & QueenSide) {
+        Coords c = Coords::from_index(move.source_square);
+        Coords rook_source{0, c.y};
+        int8_t old_rook = ret.squares[rook_source.to_index()];
+        ret.squares[rook_source.to_index()] = Piece::None;
+        Coords rook_dest{3, c.y};
+        ret.squares[rook_dest.to_index()] = old_rook;
+    }
+
     return ret;
 }