diff --git a/tests/unit/framework/db/pgsql/PostgreSQLConnectionTest.php b/tests/unit/framework/db/pgsql/PostgreSQLConnectionTest.php
index f9d6e1fa3a..283edfd31e 100644
--- a/tests/unit/framework/db/pgsql/PostgreSQLConnectionTest.php
+++ b/tests/unit/framework/db/pgsql/PostgreSQLConnectionTest.php
@@ -71,7 +71,7 @@ class PostgreSQLConnectionTest extends ConnectionTest
 		$transaction->commit();
 
 		$transaction = $connection->beginTransaction();
-		$transaction->setIsolationLevel(Transaction::SERIALIZABLE . ' READ ONLY DEFERABLE');
+		$transaction->setIsolationLevel(Transaction::SERIALIZABLE . ' READ ONLY DEFERRABLE');
 		$transaction->commit();
 	}
 }