diff --git a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
index f3b5d1b..9b47bd0 100644
--- a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
+++ b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
@@ -682,7 +682,7 @@ public function providerTestInvalidDateDiff() {
    *
    * @dataProvider providerTestInvalidConstructor
    */
-  public function testInvalidConstructor($time, $errors) {
+  public function testInvalidConstructor($time, array $errors) {
     $date = new DateTimePlus($time);
 
     // Make sure the parsed date/time has errors.
@@ -731,7 +731,12 @@ public function providerTestInvalidConstructor() {
           'Double timezone specification',
         ],
       ],
-      ['2017-13-55', ['Unexpected character']],
+      [
+        '2017-13-55',
+        [
+          'Unexpected character',
+        ],
+      ],
       [
         'YYYY-MM-DD hh:mm:ss',
         [