diff --git a/mandel.s b/mandel.s
index 76816c2..0400003 100644
--- a/mandel.s
+++ b/mandel.s
@@ -980,7 +980,7 @@ keep_going:
     all_done:
     .endmacro
 
-    ; 8.24: (-128 .. 127.9) / (-8 .. +7.9)
+    ; 8.24: (-128 .. 127.9)
     ; zx = zx_2  - zy_2  + cx
     sub32 zx, zx_2, zy_2
     add32 zx, zx, cx
@@ -991,7 +991,7 @@ keep_going:
     add32 zy, zy, cy
     quick_exit zy, 2
 
-    ; convert 8.24 -> 4.12
+    ; convert 8.24 -> 4.12: (-8 .. +7.9)
     shift_round_16 zx, 4
     shift_round_16 zy, 4
 
@@ -1042,10 +1042,10 @@ z_buffer_loop:
 
     ; Compare the previously stored z values
     ldy #0
-    z_compare zx
-    z_compare zx + 1
-    z_compare zy
-    z_compare zy + 1
+    z_compare zx + 2
+    z_compare zx + 3
+    z_compare zy + 2
+    z_compare zy + 3
 
     cpy #4
     bne z_no_matches
@@ -1060,10 +1060,10 @@ z_no_matches:
 z_nothing_to_read:
 
     ; Store and expand
-    z_store zx
-    z_store zx + 1
-    z_store zy
-    z_store zy + 1
+    z_store zx + 2
+    z_store zx + 3
+    z_store zy + 2
+    z_store zy + 3
     z_advance
     stx z_buffer_end