diff --git a/src/mame/machine/bonzeadv.c b/src/mame/machine/bonzeadv.c
index 569cf5b6f55..e193d9789a6 100644
--- a/src/mame/machine/bonzeadv.c
+++ b/src/mame/machine/bonzeadv.c
@@ -380,6 +380,7 @@ WRITE16_MEMBER(asuka_state::bonzeadv_cchip_ram_w)
 {
 //  if (space.device().safe_pc()!=0xa028)
 //  logerror("%08x:  write %04x %04x cchip\n", space.device().safe_pc(), offset, data);
+	data &= mem_mask;
 
 	if (m_current_bank == 0)
 	{
diff --git a/src/mame/machine/rainbow.c b/src/mame/machine/rainbow.c
index f6bf3204a1f..627c54fac36 100644
--- a/src/mame/machine/rainbow.c
+++ b/src/mame/machine/rainbow.c
@@ -780,6 +780,8 @@ WRITE16_MEMBER(rbisland_state::rbisland_cchip_bank_w)
 
 WRITE16_MEMBER(rbisland_state::rbisland_cchip_ram_w)
 {
+	data &= mem_mask;
+
 	m_CRAM[m_current_bank][offset] = data;
 }
 
diff --git a/src/mame/video/tumbleb.c b/src/mame/video/tumbleb.c
index 42be1c72777..32bb1570fec 100644
--- a/src/mame/video/tumbleb.c
+++ b/src/mame/video/tumbleb.c
@@ -24,6 +24,8 @@ to switch between 8*8 tiles and 16*16 tiles.
 
 WRITE16_MEMBER(tumbleb_state::bcstory_tilebank_w)
 {
+	data &= mem_mask;
+
 	m_tilebank = data;
 	m_pf1_tilemap->mark_all_dirty();
 	m_pf1_alt_tilemap->mark_all_dirty();
@@ -32,6 +34,8 @@ WRITE16_MEMBER(tumbleb_state::bcstory_tilebank_w)
 
 WRITE16_MEMBER(tumbleb_state::chokchok_tilebank_w)
 {
+	data &= mem_mask;
+
 	m_tilebank = data << 1;
 	m_pf1_tilemap->mark_all_dirty();
 	m_pf1_alt_tilemap->mark_all_dirty();
@@ -50,6 +54,8 @@ WRITE16_MEMBER(tumbleb_state::wlstar_tilebank_w)
 
 WRITE16_MEMBER(tumbleb_state::suprtrio_tilebank_w)
 {
+	data &= mem_mask;
+
 	m_tilebank = data << 14; // shift it here, makes using bcstory_tilebank easier
 	m_pf1_tilemap->mark_all_dirty();
 	m_pf1_alt_tilemap->mark_all_dirty();