diff --git a/CHANGELOG.md b/CHANGELOG.md
index f591acea5..73a3ef1e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## 6.21.1 - 2018-11-12
+* [#548](https://github.com/stripe/stripe-php/pull/548) Don't mutate `Exception` class properties from `OAuthBase` error
+
 ## 6.21.0 - 2018-11-08
 * [#537](https://github.com/stripe/stripe-php/pull/537) Add new API endpoints for the `Invoice` resource.
 
diff --git a/VERSION b/VERSION
index 7ecad1405..476d3ceb7 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.21.0
+6.21.1
diff --git a/lib/Stripe.php b/lib/Stripe.php
index 2c2c38246..7ad3db931 100644
--- a/lib/Stripe.php
+++ b/lib/Stripe.php
@@ -52,7 +52,7 @@ class Stripe
     // @var float Initial delay between retries, in seconds
     private static $initialNetworkRetryDelay = 0.5;
 
-    const VERSION = '6.21.0';
+    const VERSION = '6.21.1';
 
     /**
      * @return string The API key used for requests.