diff --git a/tmp/lanelet2_extension/test/src/test_regulatory_elements.cpp b/tmp/lanelet2_extension/test/src/test_regulatory_elements.cpp
index 7037e951..25e5694c 100644
--- a/tmp/lanelet2_extension/test/src/test_regulatory_elements.cpp
+++ b/tmp/lanelet2_extension/test/src/test_regulatory_elements.cpp
@@ -16,6 +16,8 @@
 
 #include "lanelet2_extension/regulatory_elements/autoware_traffic_light.hpp"
 
+#include <boost/optional/optional_io.hpp>
+
 #include <gtest/gtest.h>
 #include <lanelet2_core/Attribute.h>
 #include <lanelet2_core/LaneletMap.h>