diff --git a/psalm.xml b/psalm.xml
index e85514adeb..d089e14123 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -2,6 +2,7 @@
 <psalm
     autoloader="test/bootstrap-static.php"
     totallyTyped="true"
+    sealAllMethods="true"
     resolveFromConfigFile="true"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="https://getpsalm.org/schema/config"