diff --git a/src/BaseAttribute.php b/src/BaseAttribute.php
index 6b7d9d5..0bee9fe 100644
--- a/src/BaseAttribute.php
+++ b/src/BaseAttribute.php
@@ -4,5 +4,6 @@
 /**
  * Exists just in case someone wants to grab all Psalm attributes during reflection
  */
+#[Immutable]
 abstract class BaseAttribute
 {}