diff --git a/UPGRADING.md b/UPGRADING.md
index 0875ae9310f..303319c3ce2 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -19,6 +19,9 @@ The format of this change log follows the advice given at [Keep a CHANGELOG](htt
   value.
 
   For more information see [MDL-85975](https://tracker.moodle.org/browse/MDL-85975)
+- When responding to pcntl signals, call existing signal handlers.
+
+  For more information see [MDL-87079](https://tracker.moodle.org/browse/MDL-87079)
 
 ## 4.5.7
 
diff --git a/lib/UPGRADING.md b/lib/UPGRADING.md
index 21753dd7ea1..eb0d85e9111 100644
--- a/lib/UPGRADING.md
+++ b/lib/UPGRADING.md
@@ -11,6 +11,9 @@
   value.
 
   For more information see [MDL-85975](https://tracker.moodle.org/browse/MDL-85975)
+- When responding to pcntl signals, call existing signal handlers.
+
+  For more information see [MDL-87079](https://tracker.moodle.org/browse/MDL-87079)
 
 ## 4.5.7