diff --git a/CustomHeaderSettingsForm.php b/CustomHeaderSettingsForm.php
index f3164d1..ca0d59d 100644
--- a/CustomHeaderSettingsForm.php
+++ b/CustomHeaderSettingsForm.php
@@ -24,13 +24,13 @@
 
 class CustomHeaderSettingsForm extends Form
 {
-    public int $contextId;
+    public ?int $contextId;
     public CustomHeaderPlugin $plugin;
 
     /**
      * Constructor
      */
-    public function __construct(CustomHeaderPlugin $plugin, int $contextId)
+    public function __construct(CustomHeaderPlugin $plugin, ?int $contextId)
     {
         $this->contextId = $contextId;
         $this->plugin = $plugin;