diff --git a/app/code/Magento/Webapi/Model/Config.php b/app/code/Magento/Webapi/Model/Config.php
index 53bfda46eb495629ade3733cc1b7f5783aca4b7d..fb6dc894e3c0ae87915f12bdf38311a5be541874 100644
--- a/app/code/Magento/Webapi/Model/Config.php
+++ b/app/code/Magento/Webapi/Model/Config.php
@@ -52,6 +52,7 @@ class Config
      *
      * @param WebapiCache $cache
      * @param Reader $configReader
+     * @param SerializerInterface|null $serializer
      */
     public function __construct(
         WebapiCache $cache,
diff --git a/app/code/Magento/Webapi/Model/ServiceMetadata.php b/app/code/Magento/Webapi/Model/ServiceMetadata.php
index 1b1eea3442a00a8634acbadf932063f1d6464164..14e45ccb409db24df2dd2f1c4f8d5693a55d3126 100644
--- a/app/code/Magento/Webapi/Model/ServiceMetadata.php
+++ b/app/code/Magento/Webapi/Model/ServiceMetadata.php
@@ -88,6 +88,7 @@ class ServiceMetadata
      * @param WebApiCache $cache
      * @param \Magento\Webapi\Model\Config\ClassReflector $classReflector
      * @param \Magento\Framework\Reflection\TypeProcessor $typeProcessor
+     * @param SerializerInterface|null $serializer
      */
     public function __construct(
         \Magento\Webapi\Model\Config $config,