diff --git a/src/Oro/Bundle/DataGridBundle/Extension/Sorter/ArraySorterExtension.php b/src/Oro/Bundle/DataGridBundle/Extension/Sorter/ArraySorterExtension.php
index eaff4653190..01ba6739f56 100644
--- a/src/Oro/Bundle/DataGridBundle/Extension/Sorter/ArraySorterExtension.php
+++ b/src/Oro/Bundle/DataGridBundle/Extension/Sorter/ArraySorterExtension.php
@@ -73,6 +73,10 @@ function ($currentRow, $nextRow) use ($sortingKey, $direction) {
      */
     protected function safeStringConvert($value)
     {
+        if ($value instanceof \DateTime) {
+            $value = $value->getTimestamp();
+        }
+
         return iconv('utf-8', 'ascii//TRANSLIT', strtolower((string)$value));
     }
 }