diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index 683b5e5997..2d18248eb7 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -704,7 +704,7 @@ LuaBindings::common (lua_State* L)
 		.endClass ()
 
 		.beginClass <Temporal::BBT_Time> ("BBT_TIME")
-		.addConstructor <void (*) (uint32_t, uint32_t, uint32_t)> ()
+		.addConstructor <void (*) (int32_t, int32_t, int32_t)> ()
 		.addData ("bars", &Temporal::BBT_Time::bars)
 		.addData ("beats", &Temporal::BBT_Time::beats)
 		.addData ("ticks", &Temporal::BBT_Time::ticks)
@@ -716,6 +716,10 @@ LuaBindings::common (lua_State* L)
 		// .addStaticData ("ticks_per_beat", &Temporal::ticks_per_beat, false)
 		.endClass ()
 
+		.deriveClass <Temporal::BBT_Argument, Temporal::BBT_Time> ("BBT_Argument")
+		.addConstructor <void (*) (int32_t, int32_t, int32_t)> ()
+		.endClass ()
+
 		.beginClass <Temporal::BBT_Offset> ("BBT_Offset")
 		.addConstructor <void (*) (uint32_t, uint32_t, uint32_t)> ()
 		.addData ("bars", &Temporal::BBT_Offset::bars)