diff --git a/src/mame/audio/segam1audio.cpp b/src/mame/audio/segam1audio.cpp
index 3e5a37120a3..0eb84eed88a 100644
--- a/src/mame/audio/segam1audio.cpp
+++ b/src/mame/audio/segam1audio.cpp
@@ -1,5 +1,5 @@
 // license:BSD-3-Clause
-// copyright-holders:Olivier Galibert
+// copyright-holders:R. Belmont
 /***************************************************************************
 
   Sega Model 1 sound board (68000 + 2x 315-5560 "MultiPCM")
@@ -16,7 +16,8 @@
 #define YM3438_TAG      "m1ym"
 
 static ADDRESS_MAP_START( segam1audio_map, AS_PROGRAM, 16, segam1audio_device )
-	AM_RANGE(0x000000, 0x0bffff) AM_ROM AM_REGION(":m1sndcpu", 0)
+        AM_RANGE(0x000000, 0x03ffff) AM_ROM AM_REGION(":m1sndcpu", 0)
+        AM_RANGE(0x080000, 0x09ffff) AM_ROM AM_REGION(":m1sndcpu", 0x20000) // mirror of upper ROM socket
 	AM_RANGE(0xc20000, 0xc20001) AM_READWRITE(m1_snd_68k_latch_r, m1_snd_68k_latch1_w )
 	AM_RANGE(0xc20002, 0xc20003) AM_READWRITE(m1_snd_v60_ready_r, m1_snd_68k_latch2_w )
 	AM_RANGE(0xc40000, 0xc40007) AM_DEVREADWRITE8(MULTIPCM_1_TAG, multipcm_device, read, write, 0x00ff )
diff --git a/src/mame/audio/segam1audio.h b/src/mame/audio/segam1audio.h
index e188a5502a4..9cba756c5e2 100644
--- a/src/mame/audio/segam1audio.h
+++ b/src/mame/audio/segam1audio.h
@@ -1,5 +1,5 @@
 // license:BSD-3-Clause
-// copyright-holders:Olivier Galibert
+// copyright-holders:R. Belmont
 #pragma once
 
 #ifndef __SEGAM1AUDIO_H__