diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 3801d12..614ad9e 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -1794,12 +1794,6 @@ function system_update_8301() {
 }
 
 /**
- * Clear caches to ensure Classy's message library is always added.
- */
-function system_update_8302() {
-}
-
-/**
  * Move revision metadata fields to the revision table.
  */
 function system_update_8400(&$sandbox) {
diff --git a/core/modules/system/system.post_update.php b/core/modules/system/system.post_update.php
index b96d3e3..24d245c 100644
--- a/core/modules/system/system.post_update.php
+++ b/core/modules/system/system.post_update.php
@@ -65,3 +65,9 @@ function system_post_update_hashes_clear_cache() {
 function system_post_update_timestamp_plugins() {
   // Empty post-update hook.
 }
+
+/**
+ * Clear caches to ensure Classy's message library is always added.
+ */
+function system_post_update_classy_message_library() {
+}
diff --git a/core/themes/classy/templates/misc/status-messages.html.twig b/core/themes/classy/templates/misc/status-messages.html.twig
index bc8fd10..282df38 100644
--- a/core/themes/classy/templates/misc/status-messages.html.twig
+++ b/core/themes/classy/templates/misc/status-messages.html.twig
@@ -21,7 +21,6 @@
  *   - class: HTML classes.
  */
 #}
-{{ attach_library('classy/messages') }}
 {% block messages %}
 {% for type, messages in message_list %}
   {%