diff --git a/src/calibre/devices/usbms/driver.py b/src/calibre/devices/usbms/driver.py
index 7e5706f4ea..31dc1b37c5 100644
--- a/src/calibre/devices/usbms/driver.py
+++ b/src/calibre/devices/usbms/driver.py
@@ -77,7 +77,7 @@ class USBMS(Device):
         return zip(paths, cycle([on_card]))
     
     @classmethod
-    def add_books_to_metadata(cls, locations, metadata, booklists):
+    def add_books_to_metadata(cls, locations, metadata, booklists):    
         for location in locations:
             path = location[0]
             on_card = 1 if location[1] else 0