diff --git a/mandel.s b/mandel.s
index 622ff62..86a6b48 100644
--- a/mandel.s
+++ b/mandel.s
@@ -292,16 +292,16 @@ viewport_zoom:
     .byte 6
 
 viewport_ox:
-    .word $0000
-    .word $f110
-    .word $f110
-    .word $e400
+    .dword $00000000
+    .dword $ff110000
+    .dword $ff110000
+    .dword $fe400000
 
 viewport_oy:
-    .word $0000
-    .word $fb60
-    .word $fbe0
-    .word $0000
+    .dword $00000000
+    .dword $ffb60000
+    .dword $ffbe0000
+    .dword $00000000
 
 ; 2 + 9 * byte cycles
 .macro add bytes, dest, arg1, arg2
@@ -1459,17 +1459,32 @@ zero_byte_loop:
 
     txa
     asl a
+    asl a
+
     tax
     lda viewport_ox,x
     sta ox
     lda viewport_oy,x
     sta oy
+
     inx
     lda viewport_ox,x
     sta ox + 1
     lda viewport_oy,x
     sta oy + 1
 
+    inx
+    lda viewport_ox,x
+    sta ox + 2
+    lda viewport_oy,x
+    sta oy + 2
+
+    inx
+    lda viewport_ox,x
+    sta ox + 3
+    lda viewport_oy,x
+    sta oy + 3
+
     rts
 .endproc