diff --git a/src/mame/video/wc90b.c b/src/mame/video/wc90b.c
index c8955bc2816..3bb237008b8 100644
--- a/src/mame/video/wc90b.c
+++ b/src/mame/video/wc90b.c
@@ -140,10 +140,10 @@ static void draw_sprites(running_machine *machine, bitmap_t *bitmap, const recta
 
 VIDEO_UPDATE( wc90b )
 {
-	tilemap_set_scrollx(bg_tilemap,0,8 * wc90b_scroll2x[0] + 256 - 4 + (wc90b_scroll_x_lo[0] & 0x07));
-	tilemap_set_scrolly(bg_tilemap,0,wc90b_scroll2y[0] + 1 + ((wc90b_scroll2y[0] < 0x10 || wc90b_scroll2y[0] == 0xff) ? 256 : 0));
-	tilemap_set_scrollx(fg_tilemap,0,8 * wc90b_scroll1x[0] + 256 - 6 + ((wc90b_scroll_x_lo[0] & 0x38) >> 3));
-	tilemap_set_scrolly(fg_tilemap,0,wc90b_scroll1y[0] + 1 + ((wc90b_scroll1y[0] < 0x10 || wc90b_scroll1y[0] == 0xff) ? 256 : 0));
+	tilemap_set_scrollx(bg_tilemap,0,8 * (wc90b_scroll2x[0] & 0x7f) + 256 - 4 + (wc90b_scroll_x_lo[0] & 0x07));
+	tilemap_set_scrolly(bg_tilemap,0,wc90b_scroll2y[0] + 1 + ((wc90b_scroll2x[0] & 0x80) ? 256 : 0));
+	tilemap_set_scrollx(fg_tilemap,0,8 * (wc90b_scroll1x[0] & 0x7f) + 256 - 6 + ((wc90b_scroll_x_lo[0] & 0x38) >> 3));
+	tilemap_set_scrolly(fg_tilemap,0,wc90b_scroll1y[0] + 1 + ((wc90b_scroll1x[0] & 0x80) ? 256 : 0));
 
 	tilemap_draw(bitmap,cliprect,bg_tilemap,0,0);
 	tilemap_draw(bitmap,cliprect,fg_tilemap,0,0);