diff --git a/core/includes/common.inc b/core/includes/common.inc
index e6684b5..813dce3 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -4233,7 +4233,7 @@ function drupal_render_collect_cache_tags($element, $tags = array()) {
  */
 function drupal_post_render_cache_tags_page_set($children, array $elements) {
   if (drupal_page_is_cacheable()) {
-    $tags = &drupal_static('system_cache_tags_page', FALSE);
+    $tags = &drupal_static('system_cache_tags_page', array());
     $tags = drupal_render_collect_cache_tags($elements);
   }
   return $children;
diff --git a/core/modules/node/lib/Drupal/node/NodeRenderController.php b/core/modules/node/lib/Drupal/node/NodeRenderController.php
index 62981e7..5201474 100644
--- a/core/modules/node/lib/Drupal/node/NodeRenderController.php
+++ b/core/modules/node/lib/Drupal/node/NodeRenderController.php
@@ -88,7 +88,7 @@ protected function alterBuild(array &$build, EntityInterface $entity, EntityDisp
 
     // The node 'submitted' info is not rendered in a standard way (renderable
     // array) so we have to add a cache tag manually.
-    $build['#cache']['tags']['user'][] = $entity->uid->value;
+    $build['#cache']['tags']['user'][] = $entity->getAuthorId();
   }
 
 }