diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index 0bf60ea835..4268edd4f4 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -895,6 +895,7 @@ LuaBindings::common (lua_State* L)
 		.addCast<AudioPort> ("to_audioport")
 		.addFunction ("name", &Port::name)
 		.addFunction ("pretty_name", &Port::pretty_name)
+		.addFunction ("flags", &Port::flags)
 		.addFunction ("receives_input", &Port::receives_input)
 		.addFunction ("sends_output", &Port::sends_output)
 		.addFunction ("connected", &Port::connected)