diff --git a/Classes/Controller/TerminalCommandController.php b/Classes/Controller/TerminalCommandController.php
index 780f345..c44c32e 100644
--- a/Classes/Controller/TerminalCommandController.php
+++ b/Classes/Controller/TerminalCommandController.php
@@ -90,10 +90,10 @@ public function getCommandsAction(): void
      */
     public function invokeCommandAction(
         string $commandName,
-        string $argument = null,
-        Node   $siteNode = null,
-        Node   $documentNode = null,
-        Node   $focusedNode = null
+        ?string $argument = null,
+        ?Node   $siteNode = null,
+        ?Node   $documentNode = null,
+        ?Node   $focusedNode = null
     ): void
     {
         $this->response->setContentType('application/json');
diff --git a/Classes/Domain/CommandContext.php b/Classes/Domain/CommandContext.php
index bdab2a7..9119cde 100644
--- a/Classes/Domain/CommandContext.php
+++ b/Classes/Domain/CommandContext.php
@@ -37,7 +37,7 @@ public function getSiteNode(): ?Node
         return $this->siteNode;
     }
 
-    public function withSiteNode(Node $siteNode = null): CommandContext
+    public function withSiteNode(?Node $siteNode = null): CommandContext
     {
         $instance = clone $this;
         $instance->siteNode = $siteNode;
@@ -49,7 +49,7 @@ public function getDocumentNode(): ?Node
         return $this->documentNode;
     }
 
-    public function withDocumentNode(Node $documentNode = null): CommandContext
+    public function withDocumentNode(?Node $documentNode = null): CommandContext
     {
         $instance = clone $this;
         $instance->documentNode = $documentNode;
@@ -61,7 +61,7 @@ public function getFocusedNode(): ?Node
         return $this->focusedNode;
     }
 
-    public function withFocusedNode(Node $focusedNode = null): CommandContext
+    public function withFocusedNode(?Node $focusedNode = null): CommandContext
     {
         $instance = clone $this;
         $instance->focusedNode = $focusedNode;