diff --git a/core/lib/Drupal/Core/Datetime/Element/Datetime.php b/core/lib/Drupal/Core/Datetime/Element/Datetime.php
index ff67d02..ece9e83 100644
--- a/core/lib/Drupal/Core/Datetime/Element/Datetime.php
+++ b/core/lib/Drupal/Core/Datetime/Element/Datetime.php
@@ -347,9 +347,15 @@ public static function processAjaxForm(&$element, FormStateInterface $form_state
 
     // Expose a timezone selector.
     if (!empty($element['#expose_timezone']) && $element['#expose_timezone']) {
+      $timezone_names = \DateTimeZone::listIdentifiers();
+
+      // Replace underscores with spaces within name of the timezone.
+      array_walk($timezone_names, function (&$e, $i) {
+        $e = str_replace('_', ' ', $e);
+      });
       $element['timezone'] = array(
         '#type' => 'select',
-        '#options' => array_combine(\DateTimeZone::listIdentifiers(), \DateTimeZone::listIdentifiers()),
+        '#options' => array_combine(\DateTimeZone::listIdentifiers(), $timezone_names),
         // Default to user's timezone.
         '#default_value' => $element['#date_timezone'],
         '#required' => $element['#required'],