diff --git a/dither4.s b/dither4.s
index 8689bda..2e78819 100644
--- a/dither4.s
+++ b/dither4.s
@@ -90,6 +90,10 @@ displaylist:
     lda #.hibyte(displaylist)
     sta SDLSTH
 
+    ; Disable VBI and DLI but allow Reset
+    lda #(128 + 64)
+    sta NMIEN
+
     ; Manually wait for first scan line
 wait_vblank:
     lda VCOUNT
@@ -99,11 +103,12 @@ wait_vblank:
     lda #$22
     sta SDMCTL
 
-wait_start:
+wait_loop:
     sta WSYNC
+wait_start:
     lda VCOUNT
     cmp #15
-    bne wait_start
+    bne wait_loop
     ldy #0
 
 each_scanline: