diff --git a/src/mame/drivers/jack.c b/src/mame/drivers/jack.c
index 81acce89abf..c8f3340e2d6 100644
--- a/src/mame/drivers/jack.c
+++ b/src/mame/drivers/jack.c
@@ -186,7 +186,7 @@ static ADDRESS_MAP_START( jack_map, AS_PROGRAM, 8, jack_state )
 	AM_RANGE(0xb504, 0xb504) AM_READ_PORT("IN2")
 	AM_RANGE(0xb505, 0xb505) AM_READ_PORT("IN3")
 	AM_RANGE(0xb506, 0xb507) AM_READWRITE(jack_flipscreen_r, jack_flipscreen_w)
-	AM_RANGE(0xb600, 0xb61f) AM_WRITE(jack_paletteram_w) AM_SHARE("palette")
+	AM_RANGE(0xb600, 0xb61f) AM_DEVWRITE("palette", palette_device, write) AM_SHARE("palette")
 	AM_RANGE(0xb800, 0xbbff) AM_RAM_WRITE(jack_videoram_w) AM_SHARE("videoram")
 	AM_RANGE(0xbc00, 0xbfff) AM_RAM_WRITE(jack_colorram_w) AM_SHARE("colorram")
 	AM_RANGE(0xc000, 0xffff) AM_ROM
@@ -922,7 +922,7 @@ static MACHINE_CONFIG_START( jack, jack_state )
 	MCFG_GFXDECODE_ADD("gfxdecode", "palette", jack)
 
 	MCFG_PALETTE_ADD("palette", 32)
-	MCFG_PALETTE_FORMAT(BBGGGRRR)
+	MCFG_PALETTE_FORMAT(BBGGGRRR_inverted)
 
 	/* sound hardware */
 	MCFG_SPEAKER_STANDARD_MONO("mono")
@@ -979,10 +979,9 @@ static MACHINE_CONFIG_DERIVED( joinem, jack )
 
 	MCFG_GFXDECODE_MODIFY("gfxdecode", joinem)
 
-	MCFG_PALETTE_MODIFY("palette")
-	MCFG_PALETTE_ENTRIES(0x40)
-	MCFG_PALETTE_INIT_OWNER(jack_state,joinem)
-	MCFG_PALETTE_FORMAT(BBGGGRRR)
+	MCFG_DEVICE_REMOVE("palette")
+	MCFG_PALETTE_ADD("palette", 64)
+	MCFG_PALETTE_INIT_OWNER(jack_state, joinem)
 
 	MCFG_VIDEO_START_OVERRIDE(jack_state,joinem)
 MACHINE_CONFIG_END
@@ -999,7 +998,7 @@ static MACHINE_CONFIG_DERIVED( unclepoo, joinem )
 	MCFG_SCREEN_VISIBLE_AREA(0*8, 32*8-1, 1*8, 31*8-1)
 
 	MCFG_PALETTE_MODIFY("palette")
-	MCFG_PALETTE_ENTRIES(0x100)
+	MCFG_PALETTE_ENTRIES(256)
 MACHINE_CONFIG_END
 
 
diff --git a/src/mame/includes/jack.h b/src/mame/includes/jack.h
index c108a89eaef..8c713856539 100644
--- a/src/mame/includes/jack.h
+++ b/src/mame/includes/jack.h
@@ -50,7 +50,6 @@ public:
 	DECLARE_READ8_MEMBER(striv_question_r);
 	DECLARE_WRITE8_MEMBER(jack_videoram_w);
 	DECLARE_WRITE8_MEMBER(jack_colorram_w);
-	DECLARE_WRITE8_MEMBER(jack_paletteram_w);
 	DECLARE_READ8_MEMBER(jack_flipscreen_r);
 	DECLARE_WRITE8_MEMBER(jack_flipscreen_w);
 	DECLARE_READ8_MEMBER(timer_r);
diff --git a/src/mame/video/jack.c b/src/mame/video/jack.c
index dbc6aa8725d..2ea38483d75 100644
--- a/src/mame/video/jack.c
+++ b/src/mame/video/jack.c
@@ -25,12 +25,6 @@ WRITE8_MEMBER(jack_state::jack_colorram_w)
 	m_bg_tilemap->mark_tile_dirty(offset);
 }
 
-WRITE8_MEMBER(jack_state::jack_paletteram_w)
-{
-	/* RGB output is inverted */
-	m_palette->write(space, offset, UINT8(~data));
-}
-
 READ8_MEMBER(jack_state::jack_flipscreen_r)
 {
 	flip_screen_set(offset);