diff --git a/test/http/server_sent_event_test.cpp b/test/http/server_sent_event_test.cpp
index bf39ee8..43b830d 100644
--- a/test/http/server_sent_event_test.cpp
+++ b/test/http/server_sent_event_test.cpp
@@ -1,3 +1,4 @@
+#include "boost_formatters.hpp"
 #include "http/server_sent_event.hpp"
 
 #include <boost/asio/buffer.hpp>