diff --git a/system/dummy_diag_publisher/include/dummy_diag_publisher/dummy_diag_publisher_core.hpp b/system/dummy_diag_publisher/include/dummy_diag_publisher/dummy_diag_publisher_core.hpp
index 51784f5108fc5..bbca397fb47ec 100644
--- a/system/dummy_diag_publisher/include/dummy_diag_publisher/dummy_diag_publisher_core.hpp
+++ b/system/dummy_diag_publisher/include/dummy_diag_publisher/dummy_diag_publisher_core.hpp
@@ -15,9 +15,10 @@
 #ifndef DUMMY_DIAG_PUBLISHER__DUMMY_DIAG_PUBLISHER_CORE_HPP_
 #define DUMMY_DIAG_PUBLISHER__DUMMY_DIAG_PUBLISHER_CORE_HPP_
 
-#include <diagnostic_msgs/msg/diagnostic_array.hpp>
 #include <rclcpp/rclcpp.hpp>
 
+#include <diagnostic_msgs/msg/diagnostic_array.hpp>
+
 #include <optional>
 #include <string>
 #include <vector>