diff --git a/api/src/Storage/Merge.php b/api/src/Storage/Merge.php
index 3d6092d002..2259592dfb 100644
--- a/api/src/Storage/Merge.php
+++ b/api/src/Storage/Merge.php
@@ -1261,6 +1261,7 @@ abstract class Merge
 			'!'.Api\DateTime::$user_dateformat . '* ' .Api\DateTime::$user_timeformat,
 			'!'.Api\DateTime::$user_dateformat . '*',
 			'!'.Api\DateTime::$user_dateformat,
+			'!Y-m-d\TH:i:s'
 		);
 
 		// Properly format values for spreadsheet