diff --git a/core/lib/Drupal/Core/Render/Element/MachineName.php b/core/lib/Drupal/Core/Render/Element/MachineName.php
index ace452b..33c0926 100644
--- a/core/lib/Drupal/Core/Render/Element/MachineName.php
+++ b/core/lib/Drupal/Core/Render/Element/MachineName.php
@@ -43,7 +43,8 @@
  *   - error: (optional) A custom form error message string to show, if the
  *     machine name contains disallowed characters.
  *   - standalone: (optional) Whether the live preview should stay in its own
- *     form element rather than in the suffix of the source element. Defaults
+ *     form element rather than in the suffix of the source element. The source
+ *     element must appear in the form structure before this element. Defaults
  *     to FALSE.
  * - #maxlength: (optional) Maximum allowed length of the machine name. Defaults
  *   to 64.
@@ -171,6 +172,13 @@ public static function processMachineName(&$element, FormStateInterface $form_st
       return $element;
     }
 
+    // The source element must be defined before the machine name element.
+    if (!isset($source['#id'])) {
+      $element_parents = implode('][', $element['#array_parents']);
+      $source_parents = implode('][', $element['#machine_name']['source']);
+      throw new \LogicException(sprintf('The machine name element "%s" is defined before the source element "%s", it must be defined after', $element_parents, $source_parents));
+    }
+
     $suffix_id = $source['#id'] . '-machine-name-suffix';
     $element['#machine_name']['suffix'] = '#' . $suffix_id;