diff --git a/CHANGES.md b/CHANGES.md
index 93c64891..7e3161d9 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,8 @@
 ## unreleased
 
+* mirage-crypto-ec: use sliding window method with pre-computed calues of
+  multiples of the generator point for NIST curves, speedup around 4x for P-256
+  sign (#191 @Firobe, review @palainp @hannesm)
 * mirage-crypto-ec: documentation: warn about power timing analysis on `k` in
   Dsa.sign (#195 @hannesm, as proposed by @edwintorok)
 * mirage-crypto-ec: replace internal Cstruct.t by string (speedup up to 2.5x)