diff --git a/src/Exception/Run.php b/src/Exception/Run.php
index c6fc6516..c11ad436 100644
--- a/src/Exception/Run.php
+++ b/src/Exception/Run.php
@@ -67,7 +67,7 @@ final class Run implements RunInterface
      */
     private $canThrowExceptions = true;
 
-    public function __construct(SystemFacade $system = null)
+    public function __construct(?SystemFacade $system = null)
     {
         $this->system = $system ?: new SystemFacade;
     }
diff --git a/src/Exception/Util/TemplateHelper.php b/src/Exception/Util/TemplateHelper.php
index a3054d89..407c8b50 100644
--- a/src/Exception/Util/TemplateHelper.php
+++ b/src/Exception/Util/TemplateHelper.php
@@ -234,7 +234,7 @@ public function slug($original)
      * @param string $template
      * @param array  $additionalVariables
      */
-    public function render($template, array $additionalVariables = null)
+    public function render($template, ?array $additionalVariables = null)
     {
         $variables = $this->getVariables();