diff --git a/src/wp-admin/update-core.php b/src/wp-admin/update-core.php
index 95e9dd8e43..04faf2cb83 100644
--- a/src/wp-admin/update-core.php
+++ b/src/wp-admin/update-core.php
@@ -521,7 +521,12 @@ if ( 'upgrade-core' == $action ) {
 	if ( $core || $plugins || $themes )
 		list_translation_updates();
 	unset( $core, $plugins, $themes );
-	do_action('core_upgrade_preamble');
+	/**
+	 * Fires after the core, plugin, and theme update tables.
+	 *
+	 * @since 2.9.0
+	 */
+	do_action( 'core_upgrade_preamble' );
 	echo '</div>';
 	include(ABSPATH . 'wp-admin/admin-footer.php');
 
@@ -627,5 +632,14 @@ if ( 'upgrade-core' == $action ) {
 	require_once( ABSPATH . 'wp-admin/admin-footer.php' );
 
 } else {
-	do_action('update-core-custom_' . $action);
+	/**
+	 * Fires for each custom update action on the WordPress Updates screen.
+	 *
+	 * The dynamic portion of the hook name, $action, refers to the
+	 * passed update action. The hook fires in lieu of all available
+	 * default update actions.
+	 *
+	 * @since 3.2.0
+	 */
+	do_action( "update-core-custom_{$action}" );
 }