diff --git a/.all-contributorsrc b/.all-contributorsrc
index 2d37c9b..12fcc32 100644
--- a/.all-contributorsrc
+++ b/.all-contributorsrc
@@ -78,6 +78,15 @@
         "review",
         "ideas"
       ]
+    },
+    {
+      "login": "rettinghaus",
+      "name": "Klaus Rettinghaus",
+      "avatar_url": "https://avatars.githubusercontent.com/u/7693447?v=4",
+      "profile": "https://github.com/rettinghaus",
+      "contributions": [
+        "maintenance"
+      ]
     }
   ],
   "contributorsPerLine": 7,
diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index 9180e0b..5e4e3c7 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -20,6 +20,7 @@ We use [All Contributors](https://allcontributors.org/) because we recognize tha
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/jdamerow"><img src="https://avatars.githubusercontent.com/u/8881141?v=4?s=100" width="100px;" alt="Julia Damerow"/><br /><sub><b>Julia Damerow</b></sub></a><br /><a href="https://github.com/dh-tech/undate-python/commits?author=jdamerow" title="Code">💻</a> <a href="https://github.com/dh-tech/undate-python/pulls?q=is%3Apr+reviewed-by%3Ajdamerow" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/dh-tech/undate-python/commits?author=jdamerow" title="Tests">⚠️</a> <a href="#eventOrganizing-jdamerow" title="Event Organizing">📋</a> <a href="#ideas-jdamerow" title="Ideas, Planning, & Feedback">🤔</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/maltevogl"><img src="https://avatars.githubusercontent.com/u/20907912?v=4?s=100" width="100px;" alt="Malte Vogl"/><br /><sub><b>Malte Vogl</b></sub></a><br /><a href="https://github.com/dh-tech/undate-python/commits?author=maltevogl" title="Code">💻</a> <a href="https://github.com/dh-tech/undate-python/pulls?q=is%3Apr+reviewed-by%3Amaltevogl" title="Reviewed Pull Requests">👀</a> <a href="https://github.com/dh-tech/undate-python/commits?author=maltevogl" title="Tests">⚠️</a> <a href="https://github.com/dh-tech/undate-python/commits?author=maltevogl" title="Documentation">📖</a></td>
       <td align="center" valign="top" width="14.28%"><a href="http://taylorarnold.org"><img src="https://avatars.githubusercontent.com/u/5752184?v=4?s=100" width="100px;" alt="Taylor Arnold"/><br /><sub><b>Taylor Arnold</b></sub></a><br /><a href="https://github.com/dh-tech/undate-python/pulls?q=is%3Apr+reviewed-by%3Ataylor-arnold" title="Reviewed Pull Requests">👀</a> <a href="#ideas-taylor-arnold" title="Ideas, Planning, & Feedback">🤔</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/rettinghaus"><img src="https://avatars.githubusercontent.com/u/7693447?v=4?s=100" width="100px;" alt="Klaus Rettinghaus"/><br /><sub><b>Klaus Rettinghaus</b></sub></a><br /><a href="#maintenance-rettinghaus" title="Maintenance">🚧</a></td>
     </tr>
   </tbody>
   <tfoot>