diff --git a/include/teqp/models/eos.hpp b/include/teqp/models/eos.hpp
index b57c7f0ad76ff1917e7e0ae4fa755aa62edb1027..507c406e6285421f441b82845d06c13764691559 100644
--- a/include/teqp/models/eos.hpp
+++ b/include/teqp/models/eos.hpp
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <optional>
 #include "teqp/constants.hpp"
 #include "teqp/types.hpp"