diff --git a/ReleaseNotes.md b/ReleaseNotes.md
index 4e96603d3..8351222e2 100644
--- a/ReleaseNotes.md
+++ b/ReleaseNotes.md
@@ -124,6 +124,8 @@ Paolo Tosco, Samo Turk, Riccardo Vianello
  (github pull #850 from ptosco)
   - Lines used to wedge bonds are too thick
  (github issue #852 from greglandrum)
+  - Fix out of range dereference in MCS code.
+ (github pull #857 from DoliathGavid)
 
 ## New Features and Enhancements:
   - switch to using new version of avalon toolkit