diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5556ab793c4902c5c9bdf5f5c5c12f6182da9278..cae816829a558c232b79add1e274acbd7e806d6d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@ API-breaking change is listed.
 - Make `Qc_of_Z'` not an implicit coercion (from `Z` to `Qc`) any more.
 - Make `Z.of_nat'` not an implicit coercion (from `nat` to `Z`) any more.
 - Rename `decide_left` → `decide_True_pi` and `decide_right` → `decide_False_pi`.
+- Add `option_guard_True_pi`.
 
 The following `sed` script should perform most of the renaming
 (on macOS, replace `sed` by `gsed`, installed via e.g. `brew install gnu-sed`):