diff --git a/Changelog.md b/Changelog.md
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--- a/Changelog.md
+++ b/Changelog.md
@@ -1,3 +1,8 @@
+# v0.11.28
+
+* Change to report efficiency instead of overhead.
+  Efficiency is defined by `killtime / runtime`.
+
 # v0.11.27 2023-12-01
 
 * [#1414](https://github.com/mbj/mutant/pull/1414)