diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 859659c2f1..09ef6f25d9 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -1663,6 +1663,7 @@ private:
 	uint32_t            _n_lua_scripts;
 
 	void setup_lua ();
+	void luabindings_session_rt (lua_State*);
 	void try_run_lua (pframes_t);
 
 	SerializedRCUManager<IOPlugList> _io_plugins;
diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index ea3f63c916..98cb4ffbb3 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -3449,6 +3449,20 @@ LuaBindings::session (lua_State* L)
 		.endNamespace (); // ARDOUR
 }
 
+void
+ARDOUR::Session::luabindings_session_rt (lua_State* L)
+{
+	/* declaration need to be in this file due to Windows CLASSKEYS */
+	luabridge::getGlobalNamespace (L)
+		.beginNamespace ("Ardour")
+		.beginClass <Session> ("Session")
+		/* thse are private to Session */
+		.addFunction ("rt_set_controls", &Session::rt_set_controls)
+		.addFunction ("rt_clear_all_solo_state", &Session::rt_clear_all_solo_state)
+		.endClass ()
+		.endNamespace ();
+}
+
 void
 LuaBindings::osc (lua_State* L)
 {
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index b05c314dc6..b2bab19796 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -5690,14 +5690,7 @@ Session::setup_lua ()
 	LuaBindings::stddef (L);
 	LuaBindings::common (L);
 	LuaBindings::dsp (L);
-	luabridge::getGlobalNamespace (L)
-		.beginNamespace ("Ardour")
-		.beginClass <Session> ("Session")
-		/* thse are private to Session */
-		.addFunction ("rt_set_controls", &Session::rt_set_controls)
-		.addFunction ("rt_clear_all_solo_state", &Session::rt_clear_all_solo_state)
-		.endClass ()
-		.endNamespace ();
+	luabindings_session_rt (L);
 
 	lua_mlock (L, 0);
 	luabridge::push <Session *> (L, this);