diff --git a/src/Aws/S3/Model/MultipartUpload/ParallelTransfer.php b/src/Aws/S3/Model/MultipartUpload/ParallelTransfer.php
index a71c1db899..b42c3c429f 100644
--- a/src/Aws/S3/Model/MultipartUpload/ParallelTransfer.php
+++ b/src/Aws/S3/Model/MultipartUpload/ParallelTransfer.php
@@ -90,9 +90,9 @@ protected function transfer()
             /** @var \Guzzle\Service\Command\OperationCommand $command */
             foreach ($this->client->execute($commands) as $command) {
                 $this->state->addPart(UploadPart::fromArray(array(
-                    'PartNumber'   => count($this->state) + 1,
+                    'PartNumber'   => $command['PartNumber'],
                     'ETag'         => $command->getResponse()->getEtag(),
-                    'Size'         => (int) $command->getResponse()->getContentLength(),
+                    'Size'         => (int) $command->getRequest()->getBody()->getContentLength(),
                     'LastModified' => gmdate(DateFormat::RFC2822)
                 )));
                 $eventData['command'] = $command;
diff --git a/src/Aws/S3/Model/MultipartUpload/SerialTransfer.php b/src/Aws/S3/Model/MultipartUpload/SerialTransfer.php
index 4a5953f5b2..2840dd5cb9 100644
--- a/src/Aws/S3/Model/MultipartUpload/SerialTransfer.php
+++ b/src/Aws/S3/Model/MultipartUpload/SerialTransfer.php
@@ -73,7 +73,7 @@ protected function transfer()
             $response = $command->getResponse();
 
             $this->state->addPart(UploadPart::fromArray(array(
-                'PartNumber'   => count($this->state) + 1,
+                'PartNumber'   => $command['PartNumber'],
                 'ETag'         => $response->getEtag(),
                 'Size'         => $body->getContentLength(),
                 'LastModified' => gmdate(DateFormat::RFC2822)
diff --git a/tests/Aws/Tests/S3/Integration/IntegrationTest.php b/tests/Aws/Tests/S3/Integration/IntegrationTest.php
index 985d918c84..4c13a6e619 100644
--- a/tests/Aws/Tests/S3/Integration/IntegrationTest.php
+++ b/tests/Aws/Tests/S3/Integration/IntegrationTest.php
@@ -359,7 +359,7 @@ public function testPutObjectAcl()
         ));
         $result = $command->execute();
         $this->assertContains('Grantee', (string) $command->getRequest()->getBody());
-        $this->assertEquals(array('RequestId'), array_keys($result->toArray()));
+        $this->assertArrayHasKey('RequestId', array_keys($result->toArray()));
         // Ensure that the RequestId model value is being populated correctly
         $this->assertEquals((string) $command->getResponse()->getHeader('x-amz-request-id'), $result['RequestId']);
     }
@@ -503,7 +503,7 @@ public function testMultipartUploads()
             'UploadId' => $uploadId
         ));
         $result = $command->execute();
-        $this->assertEquals(array('RequestId'), array_keys($result->toArray()));
+        $this->assertArrayHasKey('RequestId', array_keys($result->toArray()));
     }
 
     /**