diff --git a/src/Bridges/MailDI/MailExtension.php b/src/Bridges/MailDI/MailExtension.php
index f96067a..f1235a6 100644
--- a/src/Bridges/MailDI/MailExtension.php
+++ b/src/Bridges/MailDI/MailExtension.php
@@ -36,7 +36,7 @@ public function getConfigSchema(): Nette\Schema\Schema
 				Expect::structure([
 					'domain' => Expect::string()->dynamic(),
 					'selector' => Expect::string()->dynamic(),
-					'privateKey' => Expect::string()->dynamic()->required(),
+					'privateKey' => Expect::string()->required(),
 					'passPhrase' => Expect::string()->dynamic(),
 					'testMode' => Expect::bool(false)->dynamic(),
 				])->castTo('array')