diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 7feea82..56b228a 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -7,7 +7,7 @@ parameters:
     checkMissingIterableValueType: false
     paths:
         - class-wp-bootstrap-navwalker.php
-    autoload_files:
+    scanFiles:
         - tests/phpstan/class-wp-nav-menu-args.php
         - tests/phpstan/class-wp-nav-menu-item.php
         - class-wp-bootstrap-navwalker.php
@@ -22,3 +22,7 @@ parameters:
         -
             message: '#^Method WP_Bootstrap_Navwalker::(start_lvl|start_el)\(\) has no return typehint specified\.$#'
             path: class-wp-bootstrap-navwalker.php
+        # Uncertain properties.
+        -
+            message: '#^Property WP_Nav_Menu_Args::\$\S+ \(string\) in isset\(\) is not nullable\.$#'
+            path: class-wp-bootstrap-navwalker.php