diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index a3b9e0618f..e16079efb2 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -1299,11 +1299,7 @@ class Cache(object):
         string. '''
         table = self.fields['authors'].table
         result = []
-        try:
-            rmap = {icu_lower(v):k for k, v in table.id_map.iteritems()}
-        except AttributeError:
-            # Somehow, the authors table has some authors that are None. Corrupted db?
-            rmap = {icu_lower(v or ''):k for k, v in table.id_map.iteritems()}
+        rmap = {icu_lower(v):k for k, v in table.id_map.iteritems()}
         for aut in authors:
             aid = rmap.get(icu_lower(aut), None)
             result.append(author_to_author_sort(aut) if aid is None else table.asort_map[aid])
diff --git a/src/calibre/db/tables.py b/src/calibre/db/tables.py
index f2ccbe0c39..295558c313 100644
--- a/src/calibre/db/tables.py
+++ b/src/calibre/db/tables.py
@@ -56,7 +56,7 @@ class Table(object):
         }.get(metadata['datatype'], None)
         if name == 'authors':
             # Legacy
-            self.unserialize = lambda x: x.replace('|', ',') if x else None
+            self.unserialize = lambda x: x.replace('|', ',') if x else ''
 
         self.link_table = (link_table if link_table else
                 'books_%s_link'%self.metadata['table'])