diff --git a/src/mame/drivers/williams.c b/src/mame/drivers/williams.c
index cad9bdd3ebf..9042d0e66ae 100644
--- a/src/mame/drivers/williams.c
+++ b/src/mame/drivers/williams.c
@@ -1690,7 +1690,7 @@ static MACHINE_CONFIG_DERIVED( tshoot, williams2 )
 MACHINE_CONFIG_END
 
 
-static MACHINE_CONFIG_DERIVED( joust2, williams2 )
+static MACHINE_CONFIG_DERIVED_CLASS( joust2, williams2, joust2_state )
 
 	/* basic machine hardware */
 	MCFG_WILLIAMS_CVSD_SOUND_ADD("cvsd")
diff --git a/src/mame/includes/williams.h b/src/mame/includes/williams.h
index bbde5597db1..74c7f8ec087 100644
--- a/src/mame/includes/williams.h
+++ b/src/mame/includes/williams.h
@@ -13,7 +13,6 @@ class williams_state : public driver_device
 public:
 	williams_state(const machine_config &mconfig, device_type type, const char *tag)
 		: driver_device(mconfig, type, tag),
-		m_cvsd_sound(*this, "cvsd"),
 		m_nvram(*this, "nvram"),
 		m_videoram(*this, "videoram"),
 		m_blaster_palette_0(*this, "blaster_pal0"),
@@ -21,8 +20,6 @@ public:
 		m_williams2_tileram(*this, "williams2_tile")
 	{ }
 
-	optional_device<williams_cvsd_sound_device> m_cvsd_sound;
-
 	required_shared_ptr<UINT8>	m_nvram;
 	UINT8 *m_mayday_protection;
 	required_shared_ptr<UINT8> m_videoram;
@@ -78,6 +75,16 @@ public:
 };
 
 
+class joust2_state : public williams_state
+{
+public:
+	joust2_state(const machine_config &mconfig, device_type type, const char *tag)
+		: williams_state(mconfig, type, tag),
+		m_cvsd_sound(*this, "cvsd") { }
+
+	required_device<williams_cvsd_sound_device> m_cvsd_sound;
+};
+
 /*----------- defined in drivers/williams.c -----------*/
 
 void defender_install_io_space(address_space *space);
diff --git a/src/mame/machine/williams.c b/src/mame/machine/williams.c
index 3921eccc8bc..b10cc4a00cd 100644
--- a/src/mame/machine/williams.c
+++ b/src/mame/machine/williams.c
@@ -985,7 +985,7 @@ static WRITE8_DEVICE_HANDLER( tshoot_lamp_w )
 
 MACHINE_START( joust2 )
 {
-	williams_state *state = machine.driver_data<williams_state>();
+	joust2_state *state = machine.driver_data<joust2_state>();
 	MACHINE_START_CALL(williams2);
 	state_save_register_global(machine, state->m_joust2_current_sound_data);
 }
@@ -1006,7 +1006,7 @@ static TIMER_CALLBACK( joust2_deferred_snd_cmd_w )
 
 static WRITE8_DEVICE_HANDLER( joust2_pia_3_cb1_w )
 {
-	williams_state *state = device->machine().driver_data<williams_state>();
+	joust2_state *state = device->machine().driver_data<joust2_state>();
 	state->m_joust2_current_sound_data = (state->m_joust2_current_sound_data & ~0x100) | ((data << 8) & 0x100);
 	state->m_cvsd_sound->write(*device->machine().memory().first_space(), 0, state->m_joust2_current_sound_data);
 }
@@ -1014,7 +1014,7 @@ static WRITE8_DEVICE_HANDLER( joust2_pia_3_cb1_w )
 
 static WRITE8_DEVICE_HANDLER( joust2_snd_cmd_w )
 {
-	williams_state *state = device->machine().driver_data<williams_state>();
+	joust2_state *state = device->machine().driver_data<joust2_state>();
 	state->m_joust2_current_sound_data = (state->m_joust2_current_sound_data & ~0xff) | (data & 0xff);
 	state->m_cvsd_sound->write(*device->machine().memory().first_space(), 0, state->m_joust2_current_sound_data);
 	device->machine().scheduler().synchronize(FUNC(joust2_deferred_snd_cmd_w), state->m_joust2_current_sound_data);