diff --git a/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php b/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
index e99374c..ce2c441 100644
--- a/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
+++ b/core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php
@@ -136,7 +136,7 @@ public function validateStartEnd(array &$element, FormStateInterface $form_state
       if ($start_date->getTimestamp() !== $end_date->getTimestamp()) {
         $interval = $start_date->diff($end_date);
         if ($interval->invert === 1) {
-          $form_state->setError($element, $this->t('The @title end date cannot be before the start date', ['@title' => $element['#title']]));
+          $form_state->setError($element, $this->t('The end of <em>@title</em> cannot be before its start.', ['@title' => $element['#title']]));
         }
       }
     }