diff --git a/parameter_utils/parameter.hpp b/parameter_utils/parameter.hpp
index f12b29cd..57686926 100644
--- a/parameter_utils/parameter.hpp
+++ b/parameter_utils/parameter.hpp
@@ -1,3 +1,5 @@
+#pragma once
+
 #include <vector>
 #include <string>
 #include <variant>