diff --git a/core/vip.c b/core/vip.c
index ca4239f..e7ad01a 100644
--- a/core/vip.c
+++ b/core/vip.c
@@ -984,7 +984,7 @@ static void vipDrawHBias(VB *sim, World *world) {
         /* Process all visible lines */
         param = &sim->vip.ram[world->paramBase +
             ((y1 - world->gy) << 2) + (i << 1)];
-        for (y = y1; y < y2; y++, param += 2) {
+        for (y = y1; y < y2; y++, param += 4) {
 
             /* Configure window bounds */
             wnd.y1 = y;
@@ -992,7 +992,7 @@ static void vipDrawHBias(VB *sim, World *world) {
 
             /* Draw the background into the window */
             vipDrawBackground(sim->vip.shadow[i], &wnd, world,
-                mx + busReadBuffer(param, VB_S16), my);
+                mx - busReadBuffer(param, VB_S16), my);
         }
 
     }