diff --git a/mandel-core.s b/mandel-core.s
index a153ff5..abe9542 100644
--- a/mandel-core.s
+++ b/mandel-core.s
@@ -18,6 +18,7 @@ z_buffer_start:  .res 1 ; u8: index into z_buffer
 z_buffer_end:    .res 1 ; u8: index into z_buffer
 iter:            .res 1 ; u8: iteration count
 ptr:             .res 2 ; u16
+pixel_ptr:       .res 2 ; u16
 temp:            .res 2 ; u16
 temp2:           .res 2 ; u16
 
@@ -1267,21 +1268,21 @@ enough:
 negative:
     ; temp1 = top half
     lda #.lobyte(framebuffer_top + stride * half_height)
-    sta ptr
+    sta pixel_ptr
     lda #.hibyte(framebuffer_top + stride * half_height)
-    sta ptr + 1
+    sta pixel_ptr + 1
     jmp point
 
 positive:
 
     lda #.lobyte(framebuffer_bottom)
-    sta ptr
+    sta pixel_ptr
     lda #.hibyte(framebuffer_bottom)
-    sta ptr + 1
+    sta pixel_ptr + 1
 
 point:
 
-    ; ptr += sy * stride
+    ; pixel_ptr += sy * stride
     ;    temp * 40
     ; =  temp * 32  +  temp * 8
     ; = (temp << 5) + (temp << 3)
@@ -1289,10 +1290,10 @@ point:
     shl16 temp
     shl16 temp
     shl16 temp
-    add16 ptr, ptr, temp
+    add16 pixel_ptr, pixel_ptr, temp
     shl16 temp
     shl16 temp
-    add16 ptr, ptr, temp
+    add16 pixel_ptr, pixel_ptr, temp
 
     ; Ok so temp1 points to the start of the line, which is 40 bytes.
     ; Get the byte and bit offsets
@@ -1332,20 +1333,20 @@ shift_done:
 
 draw_pixel:
     ; read, mask, or, write
-    lda (ptr),y
+    lda (pixel_ptr),y
     and pixel_mask
     ora pixel_color
-    sta (ptr),y
+    sta (pixel_ptr),y
 
     dex
     beq done
     clc
     lda #40
-    adc ptr
-    sta ptr
+    adc pixel_ptr
+    sta pixel_ptr
     lda #0
-    adc ptr + 1
-    sta ptr + 1
+    adc pixel_ptr + 1
+    sta pixel_ptr + 1
     jmp draw_pixel
 
 done: