diff --git a/CHANGES.md b/CHANGES.md
index 0bfa7ccd62c..ceae1800610 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -10,6 +10,9 @@
 
 <!-- Changes that affect Black's stable style -->
 
+- Fix an infinite loop when using `#fmt: on/off` on lines with unmatching brackets.
+  (#3158)
+
 ### Preview style
 
 <!-- Changes that affect Black's preview style -->