diff --git a/lib/httpjson.php b/lib/httpjson.php
index 170f1bd..e803c79 100644
--- a/lib/httpjson.php
+++ b/lib/httpjson.php
@@ -9,14 +9,14 @@ function httpjson($endpoint,$timeout=null,$method=null,$postdata=null,$accept=nu
 		'http'=>[
 			'timeout'=>$timeout,
 			'method'=>$method,
-			'user_agent'=>'Mozilla/5.0 (X11; Linux x86_64; rv:121.0) Gecko/20100101 Firefox/121.0',
+			'user_agent'=>'httpjson/1.1',
 			'header'=>"Accept: {$accept}\r\n",
 			'ignore_errors'=>true
 		]
 	];
 	if (!is_null($token)) $context['http']['header'].="Authorization: Bearer {$token}\r\n";
 	if (!is_null($postdata)) {
-		$context['http']['header'].="Content-type: application/x-www-form-urlencoded\r\n";
+		$context['http']['header'].="Content-type: application/x-www-form-urlencoded\r\nIdempotency-Key: ".md5(implode('-',$postdata).time())."\r\n";
 		$context['http']['content']=http_build_query($postdata);
 	}
 	$context=stream_context_create($context);
@@ -46,7 +46,7 @@ function httpjson($endpoint,$timeout=null,$method=null,$postdata=null,$accept=nu
 			$errors[]="«got no headers";
 		}
 		$res=@json_decode($res,true);
-		if ($res===false) {
+		if (is_null($res)) {
 			$errors[]="got no valid JSON";
 		} else {
 			if (count($errors)>0 && isset($res['error']))