diff --git a/JsonRpc2/Controller.php b/JsonRpc2/Controller.php
index 91de207..5e7ad1f 100644
--- a/JsonRpc2/Controller.php
+++ b/JsonRpc2/Controller.php
@@ -87,7 +87,7 @@ private function getActionResponse($requestObject)
         if (!isset($this->requestObject->id) && (empty($error) || !in_array($error->getCode(), [Exception::PARSE_ERROR, Exception::INVALID_REQUEST])))
             return null;
 
-        return Helper::formatResponse($result, $error, !empty($this->requestObject->id)? $this->requestObject->id : null);
+        return Helper::formatResponse($result, $error, !isset($this->requestObject->id)? $this->requestObject->id : null);
     }
 
     /**
@@ -352,4 +352,4 @@ private function parseMethodDocComment($method)
             unset($subject);
         }
     }
-}
\ No newline at end of file
+}