diff --git a/Classes/EventListener/AfterFileProcessing.php b/Classes/EventListener/AfterFileProcessing.php
index 107333e..a68e16a 100644
--- a/Classes/EventListener/AfterFileProcessing.php
+++ b/Classes/EventListener/AfterFileProcessing.php
@@ -155,7 +155,7 @@ private function isStorageLocalAndWritable(ProcessedFile $file): bool
 
     private function originalFileIsInExcludedDirectory(FileInterface $file): bool
     {
-        $storageBasePath = $file->getStorage()->getConfiguration()['basePath'];
+        $storageBasePath = $file->getStorage()->getConfiguration()['basePath'] ?? '';
         $filePath = rtrim($storageBasePath, '/') . '/' . ltrim($file->getIdentifier(), '/');
         $excludeDirectories = array_filter(explode(';', Configuration::get('exclude_directories')));