diff --git a/include/src/core/Value.hpp b/include/src/core/Value.hpp
index 166ebab..109099d 100644
--- a/include/src/core/Value.hpp
+++ b/include/src/core/Value.hpp
@@ -8,6 +8,7 @@
 #pragma once
 
 #include <cmath>
+#include <functional>
 #include <iostream>
 #include <memory>
 #include <unordered_set>