diff --git a/lib/Service/PhotofilesService.php b/lib/Service/PhotofilesService.php
index 7eb8124f4..0e6cbe0ba 100644
--- a/lib/Service/PhotofilesService.php
+++ b/lib/Service/PhotofilesService.php
@@ -317,7 +317,7 @@ private function gatherPhotoFiles ($folder, $recursive) {
                 // we don't explore external storages for which previews are disabled
                 if ($node->isMounted()) {
                     $options = $node->getMountPoint()->getOptions();
-                    if (!$options['previews']) {
+                    if (!(array_key_exists('previews', $options) && $options['previews'])) {
                         continue;
                     }
                 }