diff --git a/z80_unpacker/example/example.sna b/z80_unpacker/example/example.sna
index 515f5d6..f9d8ac6 100644
Binary files a/z80_unpacker/example/example.sna and b/z80_unpacker/example/example.sna differ
diff --git a/z80_unpacker/unpack.asm b/z80_unpacker/unpack.asm
index 26e47b7..cb458e4 100644
--- a/z80_unpacker/unpack.asm
+++ b/z80_unpacker/unpack.asm
@@ -259,16 +259,16 @@ decode_bit:
     ; so 7*128 > 250 and thus edge case `ADD hl=(7*128+0),de=(-250)` => CF=1
 .bit_is_0_2:
  ; *** adjust probs[context_index]
-    ld      e,a                     ; preserve prob
     rra                             ; + (bit<<4) ; part of -prob_offset, needs another -16
     and     $FC                     ; clear/keep correct bits to get desired (prob>>4) + extras, CF=0
     rra
     rra
     rra                             ; A = (bit<<4) + (prob>>4), CF=(prob & 8)
     adc     a,-16                   ; A = (bit<<4) - 16 + ((prob + 8)>>4) ; -prob_offset = (bit<<4) - 16
-    sub     e                       ; A = (bit<<4) - 16 + ((prob + 8)>>4) - prob ; = ((prob + 8)>>4) - prob_offset - prob
-    neg                             ; A = prob_offset + prob - ((prob + 8)>>4)
+    ld      e,a
     pop     bc
+    ld      a,(bc)                  ; A = prob (cheaper + shorter to re-read again from memory)
+    sub     e                       ; A = 16 - (bit<<4) + prob - ((prob + 8)>>4) ; = prob_offset + prob - ((prob + 8)>>4)
     ld      (bc),a                  ; probs[context_index] = prob_offset + prob - ((prob + 8) >> 4);
     add     a,d                     ; restore CF = bit (D = bit ? $FF : $00 && A > 0)
     pop     de