diff --git a/source/extensions/transport_sockets/http_11_proxy/config.h b/source/extensions/transport_sockets/http_11_proxy/config.h
index b8580a6296d21..14918f3a5be48 100644
--- a/source/extensions/transport_sockets/http_11_proxy/config.h
+++ b/source/extensions/transport_sockets/http_11_proxy/config.h
@@ -21,6 +21,8 @@ class UpstreamHttp11ConnectSocketConfigFactory
       Server::Configuration::TransportSocketFactoryContext& context) override;
 };
 
+DECLARE_FACTORY(UpstreamHttp11ConnectSocketConfigFactory);
+
 } // namespace Http11Connect
 } // namespace TransportSockets
 } // namespace Extensions