diff --git a/src/Core/Interfaces/RequestChainableInterface.php b/src/Core/Interfaces/RequestChainableInterface.php
index c1ecf0f..5cf32a2 100644
--- a/src/Core/Interfaces/RequestChainableInterface.php
+++ b/src/Core/Interfaces/RequestChainableInterface.php
@@ -28,7 +28,7 @@ interface RequestChainableInterface
      *
      * @return self
      */
-    public function setCaller($object): self;
+    public function setCaller(?object $object);
 
     /**
      * Return the request chain heirarchy
diff --git a/src/Core/Traits/RequestChainable.php b/src/Core/Traits/RequestChainable.php
index 1d37f08..7721295 100644
--- a/src/Core/Traits/RequestChainable.php
+++ b/src/Core/Traits/RequestChainable.php
@@ -40,7 +40,7 @@ trait RequestChainable
      *
      * @return self
      */
-    public function setCaller($object): self
+    public function setCaller(?object $object)
     {
         $this->caller = $object;
         return $this;