diff --git a/mandel.s b/mandel.s
index a8f3cac..79d9c78 100644
--- a/mandel.s
+++ b/mandel.s
@@ -548,7 +548,6 @@ done:
     lda #$40
     sta ptr + 1
 
-    ldx #0
     ldy #0
 
     ; outer loop: $00 -> $3f
@@ -566,7 +565,9 @@ inner_loop:
     lda result
     sta (ptr),y
     lda result + 1
+    iny
     sta (ptr),y
+    dey
 
     ; result += 2 * arg2
     clc
@@ -594,7 +595,7 @@ inner_loop:
     inc arg2
     inc ptr + 1
     lda ptr + 1
-    cmp #$40
+    cmp #$80
     bne outer_loop
 
     rts