diff --git a/core/modules/datetime_range/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php b/core/modules/datetime_range/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php
index a23de51..16a6688 100644
--- a/core/modules/datetime_range/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php
+++ b/core/modules/datetime_range/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php
@@ -48,7 +48,7 @@ public function viewElements(FieldItemListInterface $items, $langcode) {
         /** @var \Drupal\Core\Datetime\DrupalDateTime $end_date */
         $end_date = $item->end_date;
 
-        if ($start_date->format('U') !== $end_date->format('U')) {
+        if ($this->formatDate($start_date) !== $this->formatDate($end_date)) {
           $elements[$delta] = [
             'start_date' => $this->buildDate($start_date),
             'separator' => ['#plain_text' => ' ' . $separator . ' '],
diff --git a/core/modules/datetime_range/src/Tests/DateRangeFieldTest.php b/core/modules/datetime_range/src/Tests/DateRangeFieldTest.php
index 759352e..334a0c3 100644
--- a/core/modules/datetime_range/src/Tests/DateRangeFieldTest.php
+++ b/core/modules/datetime_range/src/Tests/DateRangeFieldTest.php
@@ -557,11 +557,20 @@ public function testAlldayRangeField() {
     entity_get_display($this->field->getTargetEntityTypeId(), $this->field->getTargetBundle(), 'full')
       ->setComponent($field_name, $this->displayOptions)
       ->save();
-    $expected = $start_date->format($this->displayOptions['settings']['date_format']) . ' THESEPARATOR ' . $end_date->format($this->displayOptions['settings']['date_format']);
-    $this->renderTestEntity($id);
-    $this->assertText($expected, new FormattableMarkup('Formatted date field using daterange_custom format displayed as %expected.', array('%expected' => $expected)));
-    $this->assertText(' THESEPARATOR ', 'Found proper separator');
-
+    $start_date_rendered = $start_date->format($this->displayOptions['settings']['date_format']);
+    $end_date_rendered = $end_date->format($this->displayOptions['settings']['date_format']);
+    if ($start_date_rendered !== $end_date_rendered) {
+      $expected = $start_date_rendered . ' THESEPARATOR ' . $end_date_rendered;
+      $this->renderTestEntity($id);
+      $this->assertText($expected, new FormattableMarkup('Formatted date field using daterange_custom format displayed as %expected.', array('%expected' => $expected)));
+      $this->assertText(' THESEPARATOR ', 'Found proper separator');
+    }
+    else {
+      $expected = $start_date_rendered;
+      $this->renderTestEntity($id);
+      $this->assertText($expected, new FormattableMarkup('Formatted date field using daterange_custom format displayed as %expected.', array('%expected' => $expected)));
+      $this->assertNoText(' THESEPARATOR ', 'Not found proper separator');
+    }
   }
 
   /**