diff --git a/code/Model/SiteTreeLinkTracking.php b/code/Model/SiteTreeLinkTracking.php
index 04385714f2..309e63e8fd 100644
--- a/code/Model/SiteTreeLinkTracking.php
+++ b/code/Model/SiteTreeLinkTracking.php
@@ -79,7 +79,7 @@ public function getParser()
      * @param SiteTreeLinkTracking_Parser $parser
      * @return $this
      */
-    public function setParser(SiteTreeLinkTracking_Parser $parser = null)
+    public function setParser(?SiteTreeLinkTracking_Parser $parser = null)
     {
         $this->parser = $parser;
         return $this;
diff --git a/code/Search/SearchForm.php b/code/Search/SearchForm.php
index 95d3c72084..408cdd2c1f 100644
--- a/code/Search/SearchForm.php
+++ b/code/Search/SearchForm.php
@@ -52,10 +52,10 @@ class SearchForm extends Form
      * @param FieldList $actions Optional, defaults to a single field named "Go".
      */
     public function __construct(
-        RequestHandler $controller = null,
+        ?RequestHandler $controller = null,
         $name = 'SearchForm',
-        FieldList $fields = null,
-        FieldList $actions = null
+        ?FieldList $fields = null,
+        ?FieldList $actions = null
     ) {
         if (!$fields) {
             $fields = new FieldList(