diff --git a/include/teqp/cpp/teqpcpp.hpp b/include/teqp/cpp/teqpcpp.hpp
index a2535a34ef34cc8b2c0b36b2021edaf8f885da06..3d6c004393f89433ecb6f5f302706b9522098789 100644
--- a/include/teqp/cpp/teqpcpp.hpp
+++ b/include/teqp/cpp/teqpcpp.hpp
@@ -1,6 +1,7 @@
 #pragma once 
 #include <memory>
 #include <typeindex>
+#include <optional>
 
 #include <Eigen/Dense>
 #include "nlohmann/json.hpp"