diff --git a/README.md b/README.md
index 66382d0..aed126c 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ Pre-built PHP extensions for Heroku that are not included or fully supported by
 - [MessagePack](https://pecl.php.net/package/msgpack)
 - [igbinary](https://pecl.php.net/package/igbinary)
 
-The supported PHP versions are `7.3`, `7.4` and `8.0` on the `heroku-18` and `heroku-20` stacks.
+The supported PHP versions are `7.3`, `7.4`, `8.0` and `8.1` on the `heroku-18` and `heroku-20` stacks.
 
 Checkout the [demo app](https://php-extensions.herokuapp.com), or [browse the S3 bucket](https://s3.us-east-1.amazonaws.com/heroku-php-extensions/index.html).