diff --git a/core/includes/common.inc b/core/includes/common.inc
index 03af03b..3119fd1 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -331,11 +331,16 @@ function format_date($timestamp, $type = 'medium', $format = '', $timezone = NUL
  *
  * @return string
  *   An ISO8601 formatted date.
+ *
+ * @see \Drupal\Core\Datetime\DateFormatter::format()
+ *
+ * @deprecated in Drupal 8.0.0, will be removed before Drupal 9.0.0.
+ *   Use \Drupal::service('date.formatter')->format().
  */
 function date_iso8601($date) {
   // The DATE_ISO8601 constant cannot be used here because it does not match
   // date('c') and produces invalid RDF markup.
-  return date('c', $date);
+  return \Drupal::service('date.formatter')->format($date, 'custom', 'c', 'UTC');
 }
 
 /**
diff --git a/core/modules/rdf/tests/src/Kernel/RdfaAttributesTest.php b/core/modules/rdf/tests/src/Kernel/RdfaAttributesTest.php
index 42a4dc4..dcc4eb6 100644
--- a/core/modules/rdf/tests/src/Kernel/RdfaAttributesTest.php
+++ b/core/modules/rdf/tests/src/Kernel/RdfaAttributesTest.php
@@ -57,7 +57,7 @@ function testDatatypeCallback() {
     $datatype = 'xsd:dateTime';
 
     $date = 1252750327;
-    $iso_date = date('c', $date);
+    $iso_date = \Drupal::service('date.formatter')->format($date, 'custom', 'c', 'UTC');
 
     $mapping = array(
       'datatype' => $datatype,