diff --git a/src/mame/drivers/galaxian.cpp b/src/mame/drivers/galaxian.cpp
index 5c171e82c4c..cb0ef2cd7fc 100644
--- a/src/mame/drivers/galaxian.cpp
+++ b/src/mame/drivers/galaxian.cpp
@@ -686,7 +686,6 @@ TODO:
 - smooncrs : fix read/writes at/to unmapped memory (when player 2, "cocktail" mode) + fix the ?#! bug with "bullets" (when player 2, "cocktail" mode)
 - timefgtr : missing player bullets, sprite ROM extend(see later levels), sound is too slow, some sprites missing
 - monsterz : galaxian_state::sprites_draw "the first three sprites match against y-1", it looks like y+1 for this game (probably also applies to sfx)
-- monsterz : stars should scroll?
 - zigzag   : full Dip Switches and Inputs
 - zigzag2  : full Dip Switches and Inputs
 - jumpbug  : full Dip Switches and Inputs - missing possible discrete sounds
@@ -8887,6 +8886,12 @@ void nihon_sfx_state::init_sfx()
 	m_sfx_tilemap = true;
 }
 
+void monsterz_state::init_monsterz()
+{
+	init_sfx();
+	m_draw_background_ptr = draw_background_delegate(&galaxian_state::galaxian_draw_background, this);
+}
+
 
 void galaxian_state::init_atlantis()
 {
@@ -15522,10 +15527,10 @@ GAME( 19??, scorpionmc,  scorpion, scorpnmc,   scorpnmc,   galaxian_state,     i
 GAME( 19??, aracnis,     scorpion, scorpnmc,   aracnis,    galaxian_state,     init_batman2,  ROT90,  "bootleg",            "Aracnis (bootleg of Scorpion on Moon Cresta hardware)", MACHINE_SUPPORTS_SAVE | MACHINE_IMPERFECT_GRAPHICS )
 
 // SF-X hardware; based on Scramble with extra Z80 and 8255 driving a DAC-based sample player
-GAME( 1983, sfx,         0,        sfx,        sfx,        nihon_sfx_state, init_sfx,  ORIENTATION_FLIP_X, "Nihon Game (Nichibutsu license)",     "SF-X",         MACHINE_SUPPORTS_SAVE )
-GAME( 1983, skelagon,    sfx,      sfx,        sfx,        nihon_sfx_state, init_sfx,  ORIENTATION_FLIP_X, "Nihon Game (Nichibutsu USA license)", "Skelagon",     MACHINE_NOT_WORKING | MACHINE_SUPPORTS_SAVE)
-GAME( 1982, monsterz,    0,        monsterz,   monsterz,   monsterz_state,  init_sfx,  ORIENTATION_FLIP_X, "Nihon Game",                          "Monster Zero (set 1)", MACHINE_SUPPORTS_SAVE )
-GAME( 1982, monsterza,   monsterz, monsterz,   monsterz,   monsterz_state,  init_sfx,  ORIENTATION_FLIP_X, "Nihon Game",                          "Monster Zero (set 2)", MACHINE_SUPPORTS_SAVE )
+GAME( 1983, sfx,         0,        sfx,        sfx,        nihon_sfx_state, init_sfx,       ORIENTATION_FLIP_X, "Nihon Game (Nichibutsu license)",     "SF-X",         MACHINE_SUPPORTS_SAVE )
+GAME( 1983, skelagon,    sfx,      sfx,        sfx,        nihon_sfx_state, init_sfx,       ORIENTATION_FLIP_X, "Nihon Game (Nichibutsu USA license)", "Skelagon",     MACHINE_NOT_WORKING | MACHINE_SUPPORTS_SAVE)
+GAME( 1982, monsterz,    0,        monsterz,   monsterz,   monsterz_state,  init_monsterz,  ORIENTATION_FLIP_X, "Nihon Game",                          "Monster Zero (set 1)", MACHINE_SUPPORTS_SAVE )
+GAME( 1982, monsterza,   monsterz, monsterz,   monsterz,   monsterz_state,  init_monsterz,  ORIENTATION_FLIP_X, "Nihon Game",                          "Monster Zero (set 2)", MACHINE_SUPPORTS_SAVE )
 
 
 /*
diff --git a/src/mame/includes/galaxian.h b/src/mame/includes/galaxian.h
index 24c8f181170..f78bf776ae4 100644
--- a/src/mame/includes/galaxian.h
+++ b/src/mame/includes/galaxian.h
@@ -210,6 +210,7 @@ public:
 	void stars_update_origin();
 	void stars_draw_row(bitmap_rgb32 &bitmap, int maxx, int y, uint32_t star_offs, uint8_t starmask);
 	void null_draw_background(bitmap_rgb32 &bitmap, const rectangle &cliprect);
+	void galaxian_draw_stars(bitmap_rgb32 &bitmap, const rectangle &cliprect, int maxx);
 	void galaxian_draw_background(bitmap_rgb32 &bitmap, const rectangle &cliprect);
 	void background_draw_colorsplit(bitmap_rgb32 &bitmap, const rectangle &cliprect, rgb_t color, int split, int split_flipped);
 	void scramble_draw_stars(bitmap_rgb32 &bitmap, const rectangle &cliprect, int maxx);
@@ -814,6 +815,8 @@ public:
 
 	void monsterz(machine_config& config);
 
+	void init_monsterz();
+
 protected:
 	virtual void machine_start() override;
 
diff --git a/src/mame/video/galaxian.cpp b/src/mame/video/galaxian.cpp
index 99fe3196f2a..6f59f183d32 100644
--- a/src/mame/video/galaxian.cpp
+++ b/src/mame/video/galaxian.cpp
@@ -930,12 +930,8 @@ void galaxian_state::null_draw_background(bitmap_rgb32 &bitmap, const rectangle
 }
 
 
-
-void galaxian_state::galaxian_draw_background(bitmap_rgb32 &bitmap, const rectangle &cliprect)
+void galaxian_state::galaxian_draw_stars(bitmap_rgb32 &bitmap, const rectangle &cliprect, int maxx)
 {
-	/* erase the background to black first */
-	bitmap.fill(rgb_t::black(), cliprect);
-
 	/* update the star origin to the current frame */
 	stars_update_origin();
 
@@ -948,12 +944,21 @@ void galaxian_state::galaxian_draw_background(bitmap_rgb32 &bitmap, const rectan
 		for (y = cliprect.min_y; y <= cliprect.max_y; y++)
 		{
 			uint32_t star_offs = m_star_rng_origin + y * 512;
-			stars_draw_row(bitmap, 256, y, star_offs, 0xff);
+			stars_draw_row(bitmap, maxx, y, star_offs, 0xff);
 		}
 	}
 }
 
 
+void galaxian_state::galaxian_draw_background(bitmap_rgb32 &bitmap, const rectangle &cliprect)
+{
+	/* erase the background to black first */
+	bitmap.fill(rgb_t::black(), cliprect);
+
+	galaxian_draw_stars(bitmap, cliprect, 256);
+}
+
+
 void galaxian_state::background_draw_colorsplit(bitmap_rgb32 &bitmap, const rectangle &cliprect, rgb_t color, int split, int split_flipped)
 {
 	/* horizontal bgcolor split */