diff --git a/include/boost/beast/_experimental/test/detail/stream_state.ipp b/include/boost/beast/_experimental/test/detail/stream_state.ipp
index 268c76051c..3347c21b33 100644
--- a/include/boost/beast/_experimental/test/detail/stream_state.ipp
+++ b/include/boost/beast/_experimental/test/detail/stream_state.ipp
@@ -12,6 +12,7 @@
 #define BOOST_BEAST_TEST_DETAIL_STREAM_STATE_IPP
 
 #include <boost/beast/_experimental/test/error.hpp>
+#include <boost/asio/error.hpp>
 #include <boost/make_shared.hpp>
 
 namespace boost {