diff --git a/src/Utils/DPop.php b/src/Utils/DPop.php
index 646080f..592f53d 100644
--- a/src/Utils/DPop.php
+++ b/src/Utils/DPop.php
@@ -48,7 +48,7 @@ public function __construct(JtiValidator $jtiValidator)
 	public function getWebId($request) {
 		$serverParams = $request->getServerParams();
 
-		if (isset($serverParams['HTTP_AUTHORIZATION']) === false) {
+		if (empty($serverParams['HTTP_AUTHORIZATION'])) {
 			$webId = "public";
 		} else {
 			$this->validateRequestHeaders($serverParams);