diff --git a/cpp/src/board.hpp b/cpp/src/board.hpp
index e58ccb9..b2d8e0d 100644
--- a/cpp/src/board.hpp
+++ b/cpp/src/board.hpp
@@ -57,3 +57,8 @@ struct Board {
         return colour_at(xy.to_index());
     }
 };
+
+inline bool operator<(const Board& m1, const Board& m2) {
+    return m1.to_fen() < m2.to_fen(
+           ); // TODO: make this the comparison between the hash of the board
+}
diff --git a/cpp/src/move.hpp b/cpp/src/move.hpp
index 1e1b0f7..0f358b6 100644
--- a/cpp/src/move.hpp
+++ b/cpp/src/move.hpp
@@ -39,6 +39,10 @@ struct Move {
     }
 };
 
+inline bool operator<(const Move& m1, const Move& m2) {
+    return m1.to_string() < m2.to_string();
+}
+
 inline std::ostream& operator<<(std::ostream& os, const Move& m) {
     os << m.to_string();
     return os;