diff --git a/source/script.php b/source/script.php
index 9f949dc..91a4051 100644
--- a/source/script.php
+++ b/source/script.php
@@ -145,6 +145,10 @@ class Pkg_MokoSuiteBackupInstallerScript
 		// (Joomla may not add new submenu entries or update params on upgrades)
 		$this->ensureSubmenuItems();
 
+		// Fix package client_id — packages must be client_id=0 (site) for
+		// Joomla's updater to match the <client>site</client> in updates.xml
+		$this->fixPackageClientId();
+
 		// Sync submenu icons in #__menu (Joomla doesn't update icons on upgrades)
 		$this->syncMenuIcons();
 
@@ -478,6 +482,22 @@ class Pkg_MokoSuiteBackupInstallerScript
 		}
 	}
 
+	private function fixPackageClientId(): void
+	{
+		try {
+			$db = Factory::getDbo();
+			$query = $db->getQuery(true)
+				->update($db->quoteName('#__extensions'))
+				->set($db->quoteName('client_id') . ' = 0')
+				->where($db->quoteName('element') . ' = ' . $db->quote('pkg_mokosuitebackup'))
+				->where($db->quoteName('type') . ' = ' . $db->quote('package'));
+			$db->setQuery($query);
+			$db->execute();
+		} catch (\Exception $e) {
+			error_log('MokoSuiteBackup: fixPackageClientId() failed: ' . $e->getMessage());
+		}
+	}
+
 	private function syncMenuIcons(): void
 	{
 		$iconMap = [