diff --git a/src/mame/machine/naomigd.c b/src/mame/machine/naomigd.c
index 6b688ba502e..e207b168b5a 100644
--- a/src/mame/machine/naomigd.c
+++ b/src/mame/machine/naomigd.c
@@ -394,7 +394,7 @@ void naomi_gdrom_board::device_start()
 
 	UINT64 key;
 
-	const UINT8 *picdata = memregion(pic_tag)->base();
+	const UINT8 *picdata = machine().root_device().memregion(pic_tag)->base();
 
 	if(picdata) {
 		if(machine().root_device().memregion(pic_tag)->bytes() >= 0x4000) {
diff --git a/src/mame/machine/naomim1.c b/src/mame/machine/naomim1.c
index 16d2389d032..9f889612f7b 100644
--- a/src/mame/machine/naomim1.c
+++ b/src/mame/machine/naomim1.c
@@ -31,7 +31,7 @@ void naomi_m1_board::device_start()
 {
 	naomi_board::device_start();
 
-	const UINT8 *key_data = memregion(key_tag)->base();
+	const UINT8 *key_data = machine().root_device().memregion(key_tag)->base();
 	key = (key_data[0] << 24) | (key_data[1] << 16) | (key_data[2] << 8) | key_data[3];
 	buffer = auto_alloc_array(machine(), UINT8, BUFFER_SIZE);
 
diff --git a/src/mame/machine/naomim2.c b/src/mame/machine/naomim2.c
index 7f2bf4f4bc5..eeb844365bb 100644
--- a/src/mame/machine/naomim2.c
+++ b/src/mame/machine/naomim2.c
@@ -20,7 +20,7 @@ void naomi_m2_board::device_start()
 {
 	naomi_board::device_start();
 
-	const UINT8 *key_data = memregion(key_tag)->base();
+	const UINT8 *key_data = machine().root_device().memregion(key_tag)->base();
 	key = (key_data[0] << 24) | (key_data[1] << 16) | (key_data[2] << 8) | key_data[3];
 
 	ram = auto_alloc_array(machine(), UINT8, RAM_SIZE);
diff --git a/src/mame/machine/naomim4.c b/src/mame/machine/naomim4.c
index 4f3dee94034..371bf2c589b 100644
--- a/src/mame/machine/naomim4.c
+++ b/src/mame/machine/naomim4.c
@@ -45,7 +45,7 @@ void naomi_m4_board::device_start()
 {
 	naomi_board::device_start();
 
-	const UINT8 *key_data = memregion(key_tag)->base();
+	const UINT8 *key_data = machine().root_device().memregion(key_tag)->base();
 	key = (key_data[2] << 8) | key_data[3];
 	iv = (key_data[0] << 8) | key_data[1];
 	buffer = auto_alloc_array(machine(), UINT8, BUFFER_SIZE);