diff --git a/src/Request/CreateCampaign.php b/src/Request/CreateCampaign.php
index 99a42d1..04c6e1e 100644
--- a/src/Request/CreateCampaign.php
+++ b/src/Request/CreateCampaign.php
@@ -20,6 +20,8 @@
  */
 class CreateCampaign
 {
+    const DATETIME_FORMAT = 'YmdHmi';
+
     /**
      * @var \XMLWriter $writer
      */
@@ -92,7 +94,7 @@ private function campaign(Campaign $campaign)
                 'NAME' => $campaign->getName(),
                 'STATE' => $campaign->getState(),
                 'FOLDERID' => $campaign->getFolderId(),
-                'START_DT' => $campaign->getStartDate()->format('Ymdhmi'),
+                'START_DT' => $campaign->getStartDate()->format(self::DATETIME_FORMAT),
                 'DESCRIPTION' => $campaign->getDescription(),
                 'MACATEGORY' => $campaign->getMaCategory(),
                 'PRODUCTID' => $campaign->getProductId(),
diff --git a/tests/Broadcast/CampaignTest.php b/tests/Broadcast/CampaignTest.php
index c948f1d..930cae6 100644
--- a/tests/Broadcast/CampaignTest.php
+++ b/tests/Broadcast/CampaignTest.php
@@ -49,7 +49,7 @@ public function testXml()
         $this->assertEquals($campaign->getName(), (string) $document->CAMPAIGN['NAME']);
         $this->assertEquals($campaign->getFolderId(), (int) $document->CAMPAIGN['FOLDERID']);
         $this->assertEquals($campaign->getState(), (string) $document->CAMPAIGN['STATE']);
-        $this->assertEquals($campaign->getStartDate()->format('Ymdhmi'), (string) $document->CAMPAIGN['START_DT']);
+        $this->assertEquals($campaign->getStartDate()->format(CreateCampaign::DATETIME_FORMAT), (string) $document->CAMPAIGN['START_DT']);
         $this->assertEquals($campaign->getDescription(), (string) $document->CAMPAIGN['DESCRIPTION']);
         $this->assertEquals($campaign->getMaCategory(), (string) $document->CAMPAIGN['MACATEGORY']);
         $this->assertEquals($campaign->getProductId(), (int) $document->CAMPAIGN['PRODUCTID']);