diff --git a/wx/WxClient.php b/wx/WxClient.php
index 3f24cf1..8606db1 100644
--- a/wx/WxClient.php
+++ b/wx/WxClient.php
@@ -247,7 +247,7 @@ class WxClient
 	private function structure($body, $_data)
 	{
 		$this->setIsSSL(false);
-		$this->setHeaders(null);
+		$this->setHeaders([]);
 
 		if ($this->callback !== NULL) {
 			$result = call_user_func($this->callback, $body, $_data);