diff --git a/include/boost/beast/websocket/impl/accept.hpp b/include/boost/beast/websocket/impl/accept.hpp
index aa6b05c8..4cd9bb84 100644
--- a/include/boost/beast/websocket/impl/accept.hpp
+++ b/include/boost/beast/websocket/impl/accept.hpp
@@ -145,7 +145,7 @@ build_response(
     res.result(http::status::switching_protocols);
     res.version(req.version());
     res.set(http::field::upgrade, "websocket");
-    res.set(http::field::connection, "upgrade");
+    res.set(http::field::connection, "Upgrade");
     {
         detail::sec_ws_accept_type acc;
         detail::make_sec_ws_accept(acc, key);
diff --git a/include/boost/beast/websocket/impl/stream_impl.hpp b/include/boost/beast/websocket/impl/stream_impl.hpp
index d32f1dc9..615b4beb 100644
--- a/include/boost/beast/websocket/impl/stream_impl.hpp
+++ b/include/boost/beast/websocket/impl/stream_impl.hpp
@@ -632,7 +632,7 @@ build_request(
     req.method(http::verb::get);
     req.set(http::field::host, host);
     req.set(http::field::upgrade, "websocket");
-    req.set(http::field::connection, "upgrade");
+    req.set(http::field::connection, "Upgrade");
     detail::make_sec_ws_key(key);
     req.set(http::field::sec_websocket_key, to_string_view(key));
     req.set(http::field::sec_websocket_version, "13");