diff --git a/src/mame/drivers/unkhorse.c b/src/mame/drivers/unkhorse.c
index c78fc276fc0..189e89afee9 100644
--- a/src/mame/drivers/unkhorse.c
+++ b/src/mame/drivers/unkhorse.c
@@ -75,7 +75,7 @@ static ADDRESS_MAP_START( horse_map, AS_PROGRAM, 8, horse_state )
 	AM_RANGE(0x0000, 0x37ff) AM_ROM
 	AM_RANGE(0x4000, 0x40ff) AM_DEVREADWRITE("i8155", i8155_device, memory_r, memory_w)
 	AM_RANGE(0x6000, 0x7fff) AM_RAM AM_BASE(m_video_ram)
-	AM_RANGE(0x8000, 0x8fff) AM_RAM AM_BASE(m_color_ram) AM_MIRROR(0x0860)
+	AM_RANGE(0x8000, 0x879f) AM_RAM AM_BASE(m_color_ram) AM_MIRROR(0x0860)
 	
 ADDRESS_MAP_END