diff --git a/ChangeLog b/ChangeLog
index 2e21e7521..8787d69fb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,11 @@
 
 	* src/cff/cf2font.c (cf2_computeDarkening): Avoid division by zero.
 
+	Note that the old code avoided using a region of the piecewise
+	linear function where the slope was zero.  The recovery was to use a
+	different section of the function, which produced a different,
+	incorrect amount of darkening.
+
 2013-10-02  Darrell Bellert  <darrell.bellert@hl.konicaminolta.us>
 
 	* src/sfnt/ttload.c (tt_face_load_pclt): Fix `pclt_fields'.