diff --git a/src/library/kernel_serializer.h b/src/library/kernel_serializer.h
index 7bf85c1e3..341181964 100644
--- a/src/library/kernel_serializer.h
+++ b/src/library/kernel_serializer.h
@@ -5,6 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
+#include <string>
 #include "util/serializer.h"
 #include "kernel/definition.h"