diff --git a/lib/Paymill/Models/Request/Checksum.php b/lib/Paymill/Models/Request/Checksum.php
index 4828b27..50ac7f9 100755
--- a/lib/Paymill/Models/Request/Checksum.php
+++ b/lib/Paymill/Models/Request/Checksum.php
@@ -124,9 +124,9 @@ class Checksum extends Base
     /**
      * Client identifier 
      * 
-     * @var string $_clientId
+     * @var string $_client
      */
-    private $_clientId;
+    private $_client;
 
     /**
      * Reusable payment
@@ -157,9 +157,9 @@ function __construct()
      * 
      * @return $this
      */
-    public function setClientId($clientId)
+    public function setClient($client)
     {
-        $this->_clientId = $clientId;
+        $this->_client = $client;
 
         return $this;
     }
@@ -169,9 +169,9 @@ public function setClientId($clientId)
      * 
      * @return string
      */
-    public function getClientId()
+    public function getClient()
     {
-        return $this->_clientId;
+        return $this->_client;
     }
 
     /**
@@ -683,8 +683,8 @@ public function parameterize($method)
                     $parameterArray['reusable_payment_description'] = $this->getReusablePaymentDescription();
                 }
 
-                if($this->getClientId()) {
-                    $parameterArray['client_id'] = $this->getClientId();
+                if($this->getClient()) {
+                    $parameterArray['client'] = $this->getClient();
                 }
 
                 // Unite params:
diff --git a/tests/unit/Paymill/Models/Request/ChecksumTest.php b/tests/unit/Paymill/Models/Request/ChecksumTest.php
index c388f32..96bc2fc 100755
--- a/tests/unit/Paymill/Models/Request/ChecksumTest.php
+++ b/tests/unit/Paymill/Models/Request/ChecksumTest.php
@@ -42,7 +42,7 @@ protected function tearDown()
     public function setGetTest()
     {
         $sample = array(
-            'client_id'     => 'client_88a388d9dd48f86c3136',
+            'client'     => 'client_88a388d9dd48f86c3136',
             'checksum_type' => Checksum::TYPE_PAYPAL,
             'checksum_action' => Checksum::ACTION_TRANSACTION,
             'amount'        => '200',
@@ -95,7 +95,7 @@ public function setGetTest()
         );
 
         $this->_model
-            ->setClientId($sample['client_id'])
+            ->setClient($sample['client'])
             ->setChecksumType($sample['checksum_type'])
             ->setChecksumAction($sample['checksum_action'])
             ->setAmount($sample['amount'])
@@ -112,7 +112,7 @@ public function setGetTest()
             ->setReusablePaymentDescription($sample['reusable_payment_description'])    
         ;
 
-        $this->assertEquals($this->_model->getClientId(), $sample['client_id']);
+        $this->assertEquals($this->_model->getClient(), $sample['client']);
         $this->assertEquals($this->_model->getChecksumType(), $sample['checksum_type']);
         $this->assertEquals($this->_model->getChecksumAction(), $sample['checksum_action']);
         $this->assertEquals($this->_model->getAmount(),       $sample['amount']);
@@ -162,7 +162,7 @@ public function parameterizeTestGetOne(Checksum $model)
     public function parameterizeTestCreate(Checksum $model)
     {
         $parameterArray = array();
-        $parameterArray['client_id'] = 'client_88a388d9dd48f86c3136';
+        $parameterArray['client']        = 'client_88a388d9dd48f86c3136';
         $parameterArray['checksum_type'] = Checksum::TYPE_PAYPAL;
         $parameterArray['checksum_action'] = Checksum::ACTION_TRANSACTION;
         $parameterArray['amount']        = '200';