diff --git a/src/DI/BackgroundQueueExtension.php b/src/DI/BackgroundQueueExtension.php
index a6544bc..740eb96 100644
--- a/src/DI/BackgroundQueueExtension.php
+++ b/src/DI/BackgroundQueueExtension.php
@@ -36,7 +36,7 @@ public function getConfigSchema(): Schema
 			'locksDir' => Expect::string()->required(),
 			'queue' => Expect::string()->required(),
 			'bulkSize' => Expect::int(1)->min(1),
-			'priorities' => Expect::arrayOf(Expect::int()->min(1))->default([1])->mergeDefaults(false),
+			'priorities' => Expect::arrayOf(Expect::int()->min(1)->max(999))->default([1])->mergeDefaults(false),
 			'connection' => Expect::anyOf('string', Expect::arrayOf('int|string|object', 'string')),
 			'tableName' => Expect::string('background_job'),
 			'producer' => Expect::string()->nullable(),