diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c66fcd..55a06b2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,7 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
-## [0.2.1] — 2026-09-25
+## [0.2.1] — 2026-09-19
 
 ### Fixed
 
diff --git a/CITATION.cff b/CITATION.cff
index 02babb4..4f9c476 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -13,7 +13,8 @@ authors:
   orcid: https://orcid.org/0000-0002-7292-3002
   affiliation: "Institute of Earth Sciences, University of Iceland, Reykjavik, Iceland"
 version: "0.2.1"
-date-released: "2026-09-25"
+date-released: "2026-09-19"
+doi: "10.5281/zenodo.22846130"
 url: "https://github.com/ocean-uhh/ctdcast"
 repository-code: "https://github.com/ocean-uhh/ctdcast"
 license: MIT
diff --git a/README.md b/README.md
index 7a66526..1089048 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,7 @@
 [![Python 3.10–3.13](https://img.shields.io/badge/python-3.10%20–%203.13-blue?logo=python&logoColor=white)](https://www.python.org)
 [![License: MIT](https://img.shields.io/badge/license-MIT-green)](https://opensource.org/licenses/MIT)
 [![Docs](https://img.shields.io/badge/docs-gh--pages-blue)](https://ocean-uhh.github.io/ctdcast/)
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.22846130.svg)](https://doi.org/10.5281/zenodo.22846130)
 
 Processing and reporting for shipboard CTD and LADCP data: from raw instrument files
 through QC'd, CF/CCHDO-aligned netCDF and a compiled profiles grid, to self-contained HTML.