diff --git a/src/mame/drivers/mermaid.cpp b/src/mame/drivers/mermaid.cpp
index 1dbd771fe4c..c792a4fea14 100644
--- a/src/mame/drivers/mermaid.cpp
+++ b/src/mame/drivers/mermaid.cpp
@@ -471,6 +471,7 @@ void mermaid_state::mermaid(machine_config &config)
 void mermaid_state::rougien(machine_config &config)
 {
 	mermaid(config);
+	m_bg_split = 1;
 
 	m_latch[0]->q_out_cb<2>().set(FUNC(mermaid_state::rougien_sample_playback_w));
 
diff --git a/src/mame/includes/mermaid.h b/src/mame/includes/mermaid.h
index 02bf1bdc055..228f34f52fb 100644
--- a/src/mame/includes/mermaid.h
+++ b/src/mame/includes/mermaid.h
@@ -38,6 +38,7 @@ public:
 		m_palette(*this, "palette"),
 		m_latch(*this, "latch%u", 1U)
 	{
+		m_bg_split = 0;
 	}
 
 	void rougien(machine_config &config);
@@ -63,6 +64,7 @@ private:
 	int m_coll_bit2;
 	int m_coll_bit3;
 	int m_coll_bit6;
+	int m_bg_split;
 	int m_bg_mask;
 	int m_bg_bank;
 	int m_rougien_gfxbank1;
diff --git a/src/mame/video/mermaid.cpp b/src/mame/video/mermaid.cpp
index 0e54bda0c89..18522971479 100644
--- a/src/mame/video/mermaid.cpp
+++ b/src/mame/video/mermaid.cpp
@@ -97,11 +97,14 @@ void mermaid_state::mermaid_fg_scroll_w(offs_t offset, uint8_t data)
 WRITE_LINE_MEMBER(mermaid_state::bg_mask_w)
 {
 	m_bg_mask = state;
+	logerror("mask %d\n", state);
 }
 
 WRITE_LINE_MEMBER(mermaid_state::bg_bank_w)
 {
 	m_bg_bank = state ? 0x100 : 0;
+	m_bg_tilemap->mark_all_dirty();
+	logerror("bank %d\n", state);
 }
 
 WRITE_LINE_MEMBER(mermaid_state::rougien_gfxbankswitch1_w)
@@ -224,11 +227,28 @@ void mermaid_state::draw_sprites( bitmap_ind16 &bitmap, const rectangle &cliprec
 
 uint32_t mermaid_state::screen_update_mermaid(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
 {
-	if (m_bg_mask)
+	if (m_bg_split)
+	{
+		constexpr int split_y = 64;
+		constexpr rectangle rr(0, 32*8-1, 0, 32*8-1);
+		m_bg_tilemap->draw(screen, m_helper_mask, rr, 0, 0);
+		for (int y = cliprect.min_y; y <= cliprect.max_y; y++)
+		{
+			int sy = y >= split_y ? 32*8 - 2 - (y - split_y) : 32*8 - split_y + y;
+			const u16 *s = &m_helper_mask.pix(sy, cliprect.min_x);
+			u16 *p = &bitmap.pix(y, cliprect.min_x);
+			memcpy(p, s, 2*(cliprect.max_x - cliprect.min_x + 1));
+		}
+
+
+		m_fg_tilemap->draw(screen, bitmap, cliprect, 0, 0);
+		draw_sprites(bitmap, cliprect);		
+	}
+	else if (m_bg_mask)
 	{
 		for (int y = cliprect.min_y; y <= cliprect.max_y; y++)
 		{
-			u16 *p = &bitmap.pix(y);
+			u16 *p = &bitmap.pix(y, cliprect.min_x);
 			for (int x = cliprect.min_x; x <= cliprect.max_x; x++)
 				*p++ = x < 26*8 ? 0x42 : 0x40;
 		}
@@ -238,8 +258,8 @@ uint32_t mermaid_state::screen_update_mermaid(screen_device &screen, bitmap_ind1
 		m_bg_tilemap->draw(screen, m_helper_mask, cliprect, 0, 0);
 		for (int y = cliprect.min_y; y <= cliprect.max_y; y++)
 		{
-			const u16 *s = &m_helper_mask.pix(y);
-			u16 *p = &bitmap.pix(y);
+			const u16 *s = &m_helper_mask.pix(y, cliprect.min_x);
+			u16 *p = &bitmap.pix(y, cliprect.min_x);
 			bool on = false;
 			for (int x = cliprect.min_x; x <= cliprect.max_x; x++)
 			{