diff --git a/core/lib/Drupal/Core/Render/Element/MachineName.php b/core/lib/Drupal/Core/Render/Element/MachineName.php
index ade3894..291f2c6 100644
--- a/core/lib/Drupal/Core/Render/Element/MachineName.php
+++ b/core/lib/Drupal/Core/Render/Element/MachineName.php
@@ -216,9 +216,16 @@ public static function validateMachineName(&$element, FormStateInterface $form_s
 
     // Verify that the machine name is unique.
     if ($element['#default_value'] !== $element['#value']) {
-      $function = $element['#machine_name']['exists'];
-      if (call_user_func($function, $element['#value'], $element, $form_state)) {
-        $form_state->setError($element, t('The machine-readable name is already in use. It must be unique.'));
+      // @todo maybe #access
+      if ($element['#disabled']) {
+        // Do not allow to change value of the disabled element.
+        $element['#value'] = $element['#default_value'];
+      }
+      else {
+        $function = $element['#machine_name']['exists'];
+        if (call_user_func($function, $element['#value'], $element, $form_state)) {
+          $form_state->setError($element, t('The machine-readable name is already in use. It must be unique.'));
+        }
       }
     }
   }