diff --git a/src/WireMock/Client/MappingBuilder.php b/src/WireMock/Client/MappingBuilder.php
index e069d2c..e3e1dd3 100644
--- a/src/WireMock/Client/MappingBuilder.php
+++ b/src/WireMock/Client/MappingBuilder.php
@@ -202,7 +202,7 @@ public function persistent()
      * @param WebhookDefinition $webhook
      * @return $this
      */
-    public function withPostServeAction(string $name, WebhookDefinition $webhook)
+    public function withPostServeAction($name, WebhookDefinition $webhook)
     {
         if (!isset($this->_postServeActions)) {
             $this->_postServeActions = array();