diff --git a/CHANGELOG.md b/CHANGELOG.md
index 21cf209..1dd362f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,12 +1,18 @@
 # Changelog
 
+## v0.3.1
+
+### Fixed issues
+* Add check and exception when a null or empty client ID is passed to the Oauth/Client class. [Issue #8](https://github.com/rhysnhall/etsy-php-sdk/issues/8)
+* Updated handleAcessTokenError() method to check for the existence of 'error_description' in the response body. [Issue #8](https://github.com/rhysnhall/etsy-php-sdk/issues/8)
+
 ## v0.3.0
 
 ### New
-* Added `config` property to the Client class. This currently only support the value '404_error' which when set to true will throw an error when a resource returns 404 instead of returning a null value. This value is unset/false by default.
+* Added `config` property to the Client class. This currently only supports the value '404_error' which when set to true will throw an error when a resource returns 404 instead of returning a null value. This value is unset/false by default.
 
 ### Fixed issues
-* Fixed breaking issue with class names in the resource updateRequest method. This issue only relates to Linux environments. [#6] (https://github.com/rhysnhall/etsy-php-sdk/issues/6)
+* Fixed breaking issue with class names in the resource updateRequest method. This issue only relates to Linux environments. [#6](https://github.com/rhysnhall/etsy-php-sdk/issues/6)
 
 ### Minor notes
 * Fixed some typos in Client error messages.
diff --git a/composer.json b/composer.json
index b966528..53679a2 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,6 @@
 {
   "name": "rhysnhall/etsy-php-sdk",
-  "version": "0.3.0",
+  "version": "0.3.1",
   "description": "PHP SDK for Etsy API v3.",
   "type": "library",
   "keywords": [
diff --git a/src/OAuth/Client.php b/src/OAuth/Client.php
index 43e85d4..a6cd261 100644
--- a/src/OAuth/Client.php
+++ b/src/OAuth/Client.php
@@ -42,11 +42,15 @@ class Client {
   /**
    * Create a new instance of Client.
    *
+   * @param string $client_id
    * @return void
    */
   public function __construct(
-    $client_id
+    string $client_id
   ) {
+    if(is_null($client_id) || !trim($client_id)) {
+      throw new OAuthException("No client ID found. A valid client ID is required.");
+    }
     $this->client_id = $client_id;
   }
 
@@ -264,8 +268,12 @@ private function handleAcessTokenError(\Exception $e) {
     $response = $e->getResponse();
     $body = json_decode($response->getBody(), false);
     $status_code = $response->getStatusCode();
+    $error_msg = "with error \"{$body->error}\"";
+    if($body->error_description ?? false) {
+      $error_msg .= "and message \"{$body->error_description}\"";
+    }
     throw new OAuthException(
-      "Received HTTP status code [$status_code] with error \"{$body->error}\" and message \"{$body->error_description}\" when requesting access token."
+      "Received HTTP status code [$status_code] {$error_msg} when requesting access token."
     );
   }