diff --git a/src/mame/drivers/beathead.c b/src/mame/drivers/beathead.c
index ec7e98ace5b..0cb3815c8c7 100644
--- a/src/mame/drivers/beathead.c
+++ b/src/mame/drivers/beathead.c
@@ -141,7 +141,7 @@ static TIMER_CALLBACK( scanline_callback )
 	int scanline = param;
 
 	/* update the video */
-	video_screen_update_now(0);
+	video_screen_update_now(machine->primary_screen);
 
 	/* on scanline zero, clear any halt condition */
 	if (scanline == 0)
diff --git a/src/mame/drivers/vicdual.c b/src/mame/drivers/vicdual.c
index 463652a6ff9..b8d5ca77e6a 100644
--- a/src/mame/drivers/vicdual.c
+++ b/src/mame/drivers/vicdual.c
@@ -215,7 +215,7 @@ static UINT8 *vicdual_characterram;
 
 static WRITE8_HANDLER( vicdual_videoram_w )
 {
-	video_screen_update_now(0);
+	video_screen_update_now(machine->primary_screen);
 	vicdual_videoram[offset] = data;
 }
 
@@ -228,8 +228,7 @@ UINT8 vicdual_videoram_r(offs_t offset)
 
 static WRITE8_HANDLER( vicdual_characterram_w )
 {
-	video_screen_update_now(0);
-
+	video_screen_update_now(machine->primary_screen);
 	vicdual_characterram[offset] = data;
 }