diff --git a/src/calibre/devices/mtp/filesystem_cache.py b/src/calibre/devices/mtp/filesystem_cache.py
index b1c2828b8c..dfabef06d9 100644
--- a/src/calibre/devices/mtp/filesystem_cache.py
+++ b/src/calibre/devices/mtp/filesystem_cache.py
@@ -204,7 +204,7 @@ class FilesystemCache(object):
             except KeyError:
                 # Parent does not exist, set the parent to be the storage
                 # object
-                sid = p.storage_id
+                sid = item.storage_id
                 if sid not in all_storage_ids:
                     sid = all_storage_ids[0]
                 item.parent_id = sid