diff --git a/src/calibre/devices/prs505/driver.py b/src/calibre/devices/prs505/driver.py
index 794bf66600..7277b24723 100644
--- a/src/calibre/devices/prs505/driver.py
+++ b/src/calibre/devices/prs505/driver.py
@@ -101,7 +101,8 @@ class PRS505(USBMS):
         opts = self.settings()
         collections = ['series', 'tags']
         if opts.extra_customization:
-            collections = opts.extra_customization.split(',')
+            collections = [x.strip() for x in
+                    opts.extra_customization.split(',')]
 
         c.update(blists, collections)
         c.write()
diff --git a/src/calibre/devices/usbms/books.py b/src/calibre/devices/usbms/books.py
index f7ae6c4ef4..4de1341c41 100644
--- a/src/calibre/devices/usbms/books.py
+++ b/src/calibre/devices/usbms/books.py
@@ -114,6 +114,7 @@ class BookList(_BookList):
         series_categories = set([])
         collection_attributes = list(collection_attributes)+['device_collections']
         for attr in collection_attributes:
+            attr = attr.strip()
             for book in self:
                 val = getattr(book, attr, None)
                 if not val: continue