diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1b264c0..f54fa76 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
+## Unreleased
+
+- Upgrade `pdfminer.six` from `20251230` to `20260107`. ([07a5ff6](https://github.com/jsvine/pdfplumber/commit/07a5ff6))
+
 ## 0.11.9 — 2026-01-05
 
 ### Changed