diff --git a/mandel.s b/mandel.s
index e358bee..2b1e61d 100644
--- a/mandel.s
+++ b/mandel.s
@@ -200,7 +200,7 @@ loop:
     ; zx = zx_2  + zy_2  + cx   = 3 * 20 = 60 cyc
     ; zy = zx_zy + zx_zy + cy   = 3 * 20 = 60 cyc
 
-    ; 8.24:
+    ; 8.24: (-128 .. +127.9)
     ; zx_2 = zx * zx            = 470 - 780 cyc
     ; zy_2 = zy * zy            = 470 - 780 cyc
     ; zx_zy = zx * zy           = 470 - 780 cyc