diff --git a/src/OAuth2/AuthServer.php b/src/OAuth2/AuthServer.php
index 4a360d01..2612c065 100644
--- a/src/OAuth2/AuthServer.php
+++ b/src/OAuth2/AuthServer.php
@@ -374,4 +374,24 @@ class AuthServer
         return self::$grantTypes[$grantType];
     }
 
+    /**
+     * Get a parameter from passed input parameters or the Request class
+     * @param  string|array $param Requried parameter
+     * @param  string $method      Get/put/post/delete
+     * @param  array  $inputParams Passed input parameters
+     * @return mixed               'Null' if parameter is missing
+     */
+    public static function getParam($param = '', $method = 'get', $inputParams = array())
+    {
+        if (is_string($param)) {
+            return (isset($inputParams[$param])) ? $inputParams['client_id'] : self::getRequest()->{$method}($param);
+        } else {
+            $response = array();
+            foreach ($param as $p) {
+                $response[$p] = self::getParam($p, $method, $inputParams);
+            }
+            return $response;
+        }
+    }
+
 }
diff --git a/src/OAuth2/Grant/AuthCode.php b/src/OAuth2/Grant/AuthCode.php
index b055d896..9760694e 100644
--- a/src/OAuth2/Grant/AuthCode.php
+++ b/src/OAuth2/Grant/AuthCode.php
@@ -25,31 +25,18 @@ class AuthCode implements GrantTypeInterface {
         return $this->responseType;
     }
 
-    public function completeFlow($inputParams = null, $authParams = array())
+    public function completeFlow($inputParams = null)
     {
-        // Client ID
-        $authParams['client_id'] = (isset($inputParams['client_id'])) ?
-                                    $inputParams['client_id'] :
-                                    AuthServer::getRequest()->post('client_id');
+        $authParams = AuthServer::getParam(array('client_id', 'client_secret', 'redirect_uri', 'code'), 'post', $inputParams);
 
-        if (is_null($authParams['client_id'])) {
+         if (is_null($authParams['client_id'])) {
             throw new Exception\ClientException(sprintf(AuthServer::getExceptionMessage('invalid_request'), 'client_id'), 0);
         }
 
-        // Client secret
-        $authParams['client_secret'] = (isset($inputParams['client_secret'])) ?
-                                    $inputParams['client_secret'] :
-                                    AuthServer::getRequest()->post('client_secret');
-
         if (is_null($authParams['client_secret'])) {
             throw new Exception\ClientException(sprintf(AuthServer::getExceptionMessage('invalid_request'), 'client_secret'), 0);
         }
 
-        // Redirect URI
-        $authParams['redirect_uri'] = (isset($inputParams['redirect_uri'])) ?
-                                        $inputParams['redirect_uri'] :
-                                        AuthServer::getRequest()->post('redirect_uri');
-
         if (is_null($authParams['redirect_uri'])) {
             throw new Exception\ClientException(sprintf(AuthServer::getExceptionMessage('invalid_request'), 'redirect_uri'), 0);
         }
@@ -63,11 +50,7 @@ class AuthCode implements GrantTypeInterface {
 
         $authParams['client_details'] = $clientDetails;
 
-        // The authorization code
-        $authParams['code'] = (isset($inputParams['code'])) ?
-                                $inputParams['code'] :
-                                AuthServer::getRequest()->post('code');
-
+        // Validate the authorization code
         if (is_null($authParams['code'])) {
             throw new Exception\ClientException(sprintf(AuthServer::getExceptionMessage('invalid_request'), 'code'), 0);
         }
diff --git a/src/OAuth2/Grant/GrantTypeInterface.php b/src/OAuth2/Grant/GrantTypeInterface.php
index f64b3e9f..e9444537 100644
--- a/src/OAuth2/Grant/GrantTypeInterface.php
+++ b/src/OAuth2/Grant/GrantTypeInterface.php
@@ -42,5 +42,5 @@ interface GrantTypeInterface
      * @param  array      $authParams  The authorisation paramaters that have been set so far in the request
      * @return array                   An array of parameters to be passed back to the client
      */
-    public function completeFlow($inputParams = null, $authParams = array());
+    public function completeFlow($inputParams = null);
 }