diff --git a/core/lib/Drupal/Component/Datetime/DateTimePlus.php b/core/lib/Drupal/Component/Datetime/DateTimePlus.php
index fff7c71..2e9bc02 100644
--- a/core/lib/Drupal/Component/Datetime/DateTimePlus.php
+++ b/core/lib/Drupal/Component/Datetime/DateTimePlus.php
@@ -306,8 +306,25 @@ public function render() {
    * Implements the magic __call method.
    *
    * Passes through all unknown calls onto the DateTime object.
+   *
+   * @param string $method
+   *   The method to call on the decorated object.
+   * @param array $args
+   *   Call arguments.
+   *
+   * @return mixed
+   *   The return value from the method on the decorated object. If the proxied
+   *   method call returns a DateTime object, then return the original
+   *   DateTimePlus object, which allows function chaining to work properly.
+   *   Otherwise, the value from the proxied method call is returned.
+   *
+   * @throws \Exception
+   *   Thrown when the DateTime object is not set.
+   * @throws \BadMethodCallException
+   *   Thrown when there is no corresponding method on the DateTime object to
+   *   call.
    */
-  public function __call($method, $args) {
+  public function __call($method, array $args) {
     // @todo consider using assert() as per https://www.drupal.org/node/2451793.
     if (!isset($this->dateTimeObject)) {
       throw new \Exception('DateTime object not set.');
@@ -316,17 +333,9 @@ public function __call($method, $args) {
       throw new \BadMethodCallException(sprintf('Call to undefined method %s::%s()', get_class($this), $method));
     }
 
-    $val = call_user_func_array([$this->dateTimeObject, $method], $args);
+    $result = call_user_func_array([$this->dateTimeObject, $method], $args);
 
-    // If the proxied function call returns a DateTime object, then return
-    // the original DateTimePlus object, which allows function chaining to
-    // work properly.
-    if (is_object($val) && get_class($val) === 'DateTime') {
-      return $this;
-    }
-    else {
-      return $val;
-    }
+    return $result === $this->dateTimeObject ? $this : $result;
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
index c6fcc40..2eab8db 100644
--- a/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
+++ b/core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
@@ -831,6 +831,13 @@ public function testChainable() {
     $date->setTimestamp(23456789);
     $rendered = $date->setTimezone(new \DateTimeZone('America/New_York'))->render();
     $this->assertEquals('1970-09-29 07:46:29 America/New_York', $rendered);
+
+    $date = DateTimePlus::createFromFormat('Y-m-d H:i:s', '1970-05-24 07:21:18', new \DateTimeZone('Australia/Sydney'))
+      ->setTimezone(new \DateTimeZone('America/New_York'));
+    $rendered = $date->render();
+    $this->assertInstanceOf(DateTimePlus::class, $date);
+    $this->assertEquals(12345678, $date->getTimestamp());
+    $this->assertEquals('1970-05-23 17:21:18 America/New_York', $rendered);
   }
 
   /**