core/includes/common.inc          | 4 ++--
 core/modules/system/system.module | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/core/includes/common.inc b/core/includes/common.inc
index d4fb368..f656206 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -2470,13 +2470,13 @@ function drupal_prepare_page($page) {
     $function($attachments);
   }
   if (array_diff(array_keys($attachments), ['#attached', '#post_render_cache']) !== []) {
-    throw new \LogicException('Only #attached and #post_render_cache may be set in hook_page_attachments()');
+    throw new \LogicException('Only #attached and #post_render_cache may be set in hook_page_attachments().');
   }
   // Modules and themes can alter page attachments.
   \Drupal::moduleHandler()->alter('page_attachments', $attachments);
   \Drupal::theme()->alter('page_attachments', $attachments);
   if (array_diff(array_keys($attachments), ['#attached', '#post_render_cache']) !== []) {
-    throw new \LogicException('Only #attached and #post_render_cache may be set in hook_page_attachments_alter()');
+    throw new \LogicException('Only #attached and #post_render_cache may be set in hook_page_attachments_alter().');
   }
   if (isset($attachments['#attached'])) {
     $page['#attached'] = $attachments['#attached'];
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index a4c3c09..5300b40 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -554,7 +554,7 @@ function system_page_attachments(array &$page) {
   }
 
   // Invoke hook_page_build() for modules and hook_page_alter() for both modules
-  // and, for backwards compatibility.
+  // and themes, for backwards compatibility.
   $attachments = [];
   foreach (\Drupal::moduleHandler()->getImplementations('page_build') as $module) {
     $function = $module . '_page_build';