diff --git a/src/calibre/library/database.py b/src/calibre/library/database.py
index dcebaae4e8..8c78324215 100644
--- a/src/calibre/library/database.py
+++ b/src/calibre/library/database.py
@@ -5,11 +5,12 @@ __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 Backend that implements storage of ebooks in an sqlite database.
 '''
 import sqlite3 as sqlite
-import datetime, re, cPickle, sre_constants
+import datetime, re, sre_constants
 from zlib import compress, decompress
 
 from calibre.ebooks.metadata import MetaInformation
 from calibre.ebooks.metadata import string_to_authors
+from calibre.utils.serialize import pickle_loads, pickle_dumps
 from calibre import isbytestring
 from polyglot.builtins import unicode_type
 
@@ -1090,7 +1091,7 @@ ALTER TABLE books ADD COLUMN isbn TEXT DEFAULT "" COLLATE NOCASE;
     def conversion_options(self, id, format):
         data = self.conn.get('SELECT data FROM conversion_options WHERE book=? AND format=?', (id, format.upper()), all=False)
         if data:
-            return cPickle.loads(str(data))
+            return pickle_loads(bytes(data))
         return None
 
     def has_conversion_options(self, ids, format='PIPE'):
@@ -1166,7 +1167,7 @@ ALTER TABLE books ADD COLUMN isbn TEXT DEFAULT "" COLLATE NOCASE;
             self.set_tags(id, val.split(','), append=False)
 
     def set_conversion_options(self, id, format, options):
-        data = sqlite.Binary(cPickle.dumps(options, -1))
+        data = sqlite.Binary(pickle_dumps(options))
         oid = self.conn.get('SELECT id FROM conversion_options WHERE book=? AND format=?', (id, format.upper()), all=False)
         if oid:
             self.conn.execute('UPDATE conversion_options SET data=? WHERE id=?', (data, oid))
diff --git a/src/calibre/utils/serialize.py b/src/calibre/utils/serialize.py
index 16315b77ae..2b8bd1e7cc 100644
--- a/src/calibre/utils/serialize.py
+++ b/src/calibre/utils/serialize.py
@@ -5,6 +5,7 @@
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 from polyglot.builtins import unicode_type
+from calibre.constants import ispy3
 
 
 MSGPACK_MIME = 'application/x-msgpack'
@@ -114,3 +115,24 @@ def msgpack_loads(dump):
 def json_loads(data):
     import json
     return json.loads(data, object_hook=json_decoder)
+
+
+if ispy3:
+
+    def pickle_dumps(data):
+        import pickle
+        return pickle.dumps(data, -1)
+
+    def pickle_loads(dump):
+        import pickle
+        return pickle.loads(dump, encoding='utf-8')
+
+else:
+
+    def pickle_dumps(data):
+        import cPickle as pickle
+        return pickle.dumps(data, -1)
+
+    def pickle_loads(dump):
+        import cPickle as pickle
+        return pickle.loads(dump)