diff --git a/ATTRIBUTION.md b/ATTRIBUTION.md
index 03dc17d7dd..53b1e45bc7 100644
--- a/ATTRIBUTION.md
+++ b/ATTRIBUTION.md
@@ -53,3 +53,4 @@ FairEmail uses parts or all of:
 * [tinylog 2](https://github.com/tinylog-org/tinylog). Copyright 2016-2023 Martin Winandy. [Apache License 2.0](https://github.com/tinylog-org/tinylog/blob/v2.7/license.txt).
 * [Brave Lists](https://github.com/brave/adblock-lists). [Mozilla Public License Version 2.0](https://github.com/brave/adblock-lists/blob/master/LICENSE).
 * [AG Filters Registry](https://github.com/AdguardTeam/FiltersRegistry). [GNU Lesser General Public License Version 3](https://github.com/AdguardTeam/FiltersRegistry/blob/master/LICENSE).
+* [Certificate transparency for Android and JVM](https://github.com/appmattus/certificatetransparency). Copyright 2023 Appmattus Limited. [Apache License 2.0](https://github.com/appmattus/certificatetransparency/blob/main/LICENSE.md).
diff --git a/app/src/main/assets/ATTRIBUTION.md b/app/src/main/assets/ATTRIBUTION.md
index 03dc17d7dd..53b1e45bc7 100644
--- a/app/src/main/assets/ATTRIBUTION.md
+++ b/app/src/main/assets/ATTRIBUTION.md
@@ -53,3 +53,4 @@ FairEmail uses parts or all of:
 * [tinylog 2](https://github.com/tinylog-org/tinylog). Copyright 2016-2023 Martin Winandy. [Apache License 2.0](https://github.com/tinylog-org/tinylog/blob/v2.7/license.txt).
 * [Brave Lists](https://github.com/brave/adblock-lists). [Mozilla Public License Version 2.0](https://github.com/brave/adblock-lists/blob/master/LICENSE).
 * [AG Filters Registry](https://github.com/AdguardTeam/FiltersRegistry). [GNU Lesser General Public License Version 3](https://github.com/AdguardTeam/FiltersRegistry/blob/master/LICENSE).
+* [Certificate transparency for Android and JVM](https://github.com/appmattus/certificatetransparency). Copyright 2023 Appmattus Limited. [Apache License 2.0](https://github.com/appmattus/certificatetransparency/blob/main/LICENSE.md).