diff --git a/Classes/EventListener/AddCdnToResource.php b/Classes/EventListener/AddCdnToResource.php
index e395de0..ccc2496 100644
--- a/Classes/EventListener/AddCdnToResource.php
+++ b/Classes/EventListener/AddCdnToResource.php
@@ -24,6 +24,7 @@ public function __invoke(GeneratePublicUrlForResourceEvent $event): void
         $resource = $event->getResource();
         if (
             !($driver instanceof LocalDriver) ||
+            !isset($GLOBALS['TYPO3_REQUEST']) ||
             ApplicationType::fromRequest($GLOBALS['TYPO3_REQUEST'])->isBackend()
         ) {
             return;