diff --git a/Parsedown.php b/Parsedown.php
index 38edfe92..db7b3781 100644
--- a/Parsedown.php
+++ b/Parsedown.php
@@ -346,7 +346,7 @@ protected function isBlockCompletable($Type)
     #
     # Code
 
-    protected function blockCode($Line, $Block = null)
+    protected function blockCode($Line, ?array $Block = null)
     {
         if (isset($Block) and $Block['type'] === 'Paragraph' and ! isset($Block['interrupted']))
         {