diff --git a/core/dbobject.class.php b/core/dbobject.class.php
index 63b8784c6..3924228e1 100644
--- a/core/dbobject.class.php
+++ b/core/dbobject.class.php
@@ -4730,7 +4730,7 @@ abstract class DBObject implements iDisplay
 			}
 		}
 		$oDate->modify($sModifier);
-		$this->Set($sAttCode, $oDate->format('Y-m-d H:i:s'));
+		$this->Set($sAttCode, $oDate->getTimestamp());
 	}
 
 	/**