diff --git a/core/lib/Drupal/Core/Menu/LocalTaskManager.php b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
index 5f954d1dab2..2b1e0e3009d 100644
--- a/core/lib/Drupal/Core/Menu/LocalTaskManager.php
+++ b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
@@ -168,6 +168,23 @@ class LocalTaskManager extends DefaultPluginManager {
     return call_user_func_array($controller, $arguments);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getDefinitions() {
+    $definitions =  parent::getDefinitions();
+
+    $count = 0;
+    foreach ($definitions as &$definition) {
+      if (isset($definition['weight'])) {
+        // Add some micro weight.
+        $definition['weight'] += ($count++) * 1e-6;
+      }
+    }
+
+    return $definitions;
+  }
+
   /**
    * Find all local tasks that appear on a named route.
    *
diff --git a/core/tests/Drupal/Tests/Core/Menu/LocalTaskManagerTest.php b/core/tests/Drupal/Tests/Core/Menu/LocalTaskManagerTest.php
index 579700cf82e..4768e98e6e7 100644
--- a/core/tests/Drupal/Tests/Core/Menu/LocalTaskManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Menu/LocalTaskManagerTest.php
@@ -394,7 +394,7 @@ class LocalTaskManagerTest extends UnitTestCase {
    */
   protected function getLocalTasksCache() {
     $local_task_fixtures = $this->getLocalTaskFixtures();
-    return array(
+    $local_tasks = array(
       'base_routes' => array(
         'menu_local_task_test_tasks_view' => 'menu_local_task_test_tasks_view',
       ),
@@ -414,6 +414,12 @@ class LocalTaskManagerTest extends UnitTestCase {
         ),
       ),
     );
+    $local_tasks['children']['> menu_local_task_test_tasks_view']['menu_local_task_test_tasks_settings']['weight'] = 0;
+    $local_tasks['children']['> menu_local_task_test_tasks_view']['menu_local_task_test_tasks_edit']['weight'] = 20 + 1e-6;
+    $local_tasks['children']['> menu_local_task_test_tasks_view']['menu_local_task_test_tasks_view.tab']['weight'] = 2e-6;
+    $local_tasks['children']['menu_local_task_test_tasks_view.tab']['menu_local_task_test_tasks_view_child1']['weight'] = 3e-6;
+    $local_tasks['children']['menu_local_task_test_tasks_view.tab']['menu_local_task_test_tasks_view_child2']['weight'] = 4e-6;
+    return $local_tasks;
   }
 
 }