diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index 8d19c7e9f8..283773ac58 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -336,7 +336,7 @@ class Cache(object):
         except KeyError:
             return default_value
         if field.is_multiple:
-            default_value = {} if name == 'identifiers' else ()
+            default_value = field.default_value
         try:
             return field.for_book(book_id, default_value=default_value)
         except (KeyError, IndexError):
@@ -347,6 +347,8 @@ class Cache(object):
         ' Same as field_for, except that it avoids the extra lookup to get the field object '
         if field_obj.is_composite:
             return field_obj.get_value_with_cache(book_id, self._get_proxy_metadata)
+        if field_obj.is_multiple:
+            default_value = field_obj.default_value
         try:
             return field_obj.for_book(book_id, default_value=default_value)
         except (KeyError, IndexError):
diff --git a/src/calibre/db/fields.py b/src/calibre/db/fields.py
index 9becf82403..50fa658b29 100644
--- a/src/calibre/db/fields.py
+++ b/src/calibre/db/fields.py
@@ -48,6 +48,7 @@ class Field(object):
             self._sort_key = lambda x:sort_key(calibre_langcode_to_name(x))
         self.is_multiple = (bool(self.metadata['is_multiple']) or self.name ==
                 'formats')
+        self.default_value = {} if name == 'identifiers' else () if self.is_multiple else None
         self.category_formatter = type(u'')
         if dt == 'rating':
             self.category_formatter = lambda x:'\u2605'*int(x/2)