diff --git a/src/calibre/library/__init__.py b/src/calibre/library/__init__.py
index 316961fb21..655ca84169 100644
--- a/src/calibre/library/__init__.py
+++ b/src/calibre/library/__init__.py
@@ -1,6 +1,8 @@
-from __future__ import print_function
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
+
 ''' Code to manage ebook library'''
 
 
@@ -64,7 +66,7 @@ def generate_test_db(library_path,  # {{{
 
     t = time.time() - start
     print('\nGenerated', num_of_records, 'records in:', t, 'seconds')
-    print('Time per record:', t/float(num_of_records))
+    print('Time per record:', t/num_of_records)
 # }}}
 
 
diff --git a/src/calibre/library/add_to_library.py b/src/calibre/library/add_to_library.py
index 78fa2be2e2..c284fdb141 100644
--- a/src/calibre/library/add_to_library.py
+++ b/src/calibre/library/add_to_library.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
diff --git a/src/calibre/library/caches.py b/src/calibre/library/caches.py
index 6cc8634b71..86d5a65efc 100644
--- a/src/calibre/library/caches.py
+++ b/src/calibre/library/caches.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
-from __future__ import with_statement
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
@@ -466,7 +466,7 @@ class ResultCache(SearchQueryParser):  # {{{
                 cast = lambda x: int(x)
             elif dt == 'rating':
                 cast = lambda x: 0 if x is None else int(x)
-                adjust = lambda x: x/2
+                adjust = lambda x: x//2
             elif dt in ('float', 'composite'):
                 cast = lambda x : float(x)
             else:  # count operation
@@ -851,7 +851,7 @@ class ResultCache(SearchQueryParser):  # {{{
     def _build_restriction_string(self, restriction):
         if self.base_restriction:
             if restriction:
-                return u'(%s) and (%s)' % (self.base_restriction, restriction)
+                return '(%s) and (%s)' % (self.base_restriction, restriction)
             else:
                 return self.base_restriction
         else:
@@ -867,7 +867,7 @@ class ResultCache(SearchQueryParser):  # {{{
         else:
             q = query
             if search_restriction:
-                q = u'(%s) and (%s)' % (search_restriction, query)
+                q = '(%s) and (%s)' % (search_restriction, query)
         if not q:
             if set_restriction_count:
                 self.search_restriction_book_count = len(self._map)
@@ -924,7 +924,7 @@ class ResultCache(SearchQueryParser):  # {{{
         '''
         if not hasattr(id_dict, 'items'):
             # Simple list. Make it a dict of string 'true'
-            self.marked_ids_dict = dict.fromkeys(id_dict, u'true')
+            self.marked_ids_dict = dict.fromkeys(id_dict, 'true')
         else:
             # Ensure that all the items in the dict are text
             self.marked_ids_dict = dict(zip(iter(id_dict), map(unicode_type,
@@ -1214,7 +1214,7 @@ class SortKeyGenerator(object):
                 else:
                     if self.library_order:
                         try:
-                            lang = record[self.lang_idx].partition(u',')[0]
+                            lang = record[self.lang_idx].partition(',')[0]
                         except (AttributeError, ValueError, KeyError,
                                 IndexError, TypeError):
                             lang = None
diff --git a/src/calibre/library/catalogs/bibtex.py b/src/calibre/library/catalogs/bibtex.py
index f098a2a642..e352900e65 100644
--- a/src/calibre/library/catalogs/bibtex.py
+++ b/src/calibre/library/catalogs/bibtex.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2012, Kovid Goyal <kovid@kovidgoyal.net>'
@@ -14,7 +15,7 @@ from calibre.library.catalogs import FIELDS, TEMPLATE_ALLOWED_FIELDS
 from calibre.customize.conversion import DummyReporter
 from calibre.constants import preferred_encoding
 from calibre.ebooks.metadata import format_isbn
-from polyglot.builtins import string_or_bytes, filter
+from polyglot.builtins import filter, string_or_bytes, unicode_type
 
 
 class BIBTEX(CatalogPlugin):
@@ -126,9 +127,9 @@ class BIBTEX(CatalogPlugin):
 
             bibtex_entry = []
             if mode != "misc" and check_entry_book_valid(entry) :
-                bibtex_entry.append(u'@book{')
+                bibtex_entry.append('@book{')
             elif mode != "book" :
-                bibtex_entry.append(u'@misc{')
+                bibtex_entry.append('@misc{')
             else :
                 # case strict book
                 return ''
@@ -137,7 +138,7 @@ class BIBTEX(CatalogPlugin):
                 # Citation tag
                 bibtex_entry.append(make_bibtex_citation(entry, template_citation,
                     bibtexdict))
-                bibtex_entry = [u' '.join(bibtex_entry)]
+                bibtex_entry = [' '.join(bibtex_entry)]
 
             for field in fields:
                 if field.startswith('#'):
@@ -161,68 +162,68 @@ class BIBTEX(CatalogPlugin):
                     pass
 
                 if field == 'authors' :
-                    bibtex_entry.append(u'author = "%s"' % bibtexdict.bibtex_author_format(item))
+                    bibtex_entry.append('author = "%s"' % bibtexdict.bibtex_author_format(item))
 
                 elif field == 'id' :
-                    bibtex_entry.append(u'calibreid = "%s"' % int(item))
+                    bibtex_entry.append('calibreid = "%s"' % int(item))
 
                 elif field == 'rating' :
-                    bibtex_entry.append(u'rating = "%s"' % int(item))
+                    bibtex_entry.append('rating = "%s"' % int(item))
 
                 elif field == 'size' :
-                    bibtex_entry.append(u'%s = "%s octets"' % (field, int(item)))
+                    bibtex_entry.append('%s = "%s octets"' % (field, int(item)))
 
                 elif field == 'tags' :
                     # A list to flatten
-                    bibtex_entry.append(u'tags = "%s"' % bibtexdict.utf8ToBibtex(u', '.join(item)))
+                    bibtex_entry.append('tags = "%s"' % bibtexdict.utf8ToBibtex(', '.join(item)))
 
                 elif field == 'comments' :
                     # \n removal
-                    item = item.replace(u'\r\n',u' ')
-                    item = item.replace(u'\n',u' ')
+                    item = item.replace('\r\n', ' ')
+                    item = item.replace('\n', ' ')
                     # unmatched brace removal (users should use \leftbrace or \rightbrace for single braces)
-                    item = bibtexdict.stripUnmatchedSyntax(item, u'{', u'}')
+                    item = bibtexdict.stripUnmatchedSyntax(item, '{', '}')
                     # html to text
                     try:
                         item = html2text(item)
                     except:
                         log.warn("Failed to convert comments to text")
-                    bibtex_entry.append(u'note = "%s"' % bibtexdict.utf8ToBibtex(item))
+                    bibtex_entry.append('note = "%s"' % bibtexdict.utf8ToBibtex(item))
 
                 elif field == 'isbn' :
                     # Could be 9, 10 or 13 digits
-                    bibtex_entry.append(u'isbn = "%s"' % format_isbn(item))
+                    bibtex_entry.append('isbn = "%s"' % format_isbn(item))
 
                 elif field == 'formats' :
                     # Add file path if format is selected
                     formats = [format.rpartition('.')[2].lower() for format in item]
-                    bibtex_entry.append(u'formats = "%s"' % u', '.join(formats))
+                    bibtex_entry.append('formats = "%s"' % ', '.join(formats))
                     if calibre_files:
-                        files = [u':%s:%s' % (format, format.rpartition('.')[2].upper())
+                        files = [':%s:%s' % (format, format.rpartition('.')[2].upper())
                             for format in item]
-                        bibtex_entry.append(u'file = "%s"' % u', '.join(files))
+                        bibtex_entry.append('file = "%s"' % ', '.join(files))
 
                 elif field == 'series_index' :
-                    bibtex_entry.append(u'volume = "%s"' % int(item))
+                    bibtex_entry.append('volume = "%s"' % int(item))
 
                 elif field == 'timestamp' :
-                    bibtex_entry.append(u'timestamp = "%s"' % isoformat(item).partition('T')[0])
+                    bibtex_entry.append('timestamp = "%s"' % isoformat(item).partition('T')[0])
 
                 elif field == 'pubdate' :
-                    bibtex_entry.append(u'year = "%s"' % item.year)
-                    bibtex_entry.append(u'month = "%s"' % bibtexdict.utf8ToBibtex(strftime("%b", item)))
+                    bibtex_entry.append('year = "%s"' % item.year)
+                    bibtex_entry.append('month = "%s"' % bibtexdict.utf8ToBibtex(strftime("%b", item)))
 
                 elif field.startswith('#') and isinstance(item, string_or_bytes):
-                    bibtex_entry.append(u'custom_%s = "%s"' % (field[1:],
+                    bibtex_entry.append('custom_%s = "%s"' % (field[1:],
                         bibtexdict.utf8ToBibtex(item)))
 
                 elif isinstance(item, string_or_bytes):
                     # elif field in ['title', 'publisher', 'cover', 'uuid', 'ondevice',
                     # 'author_sort', 'series', 'title_sort'] :
-                    bibtex_entry.append(u'%s = "%s"' % (field, bibtexdict.utf8ToBibtex(item)))
+                    bibtex_entry.append('%s = "%s"' % (field, bibtexdict.utf8ToBibtex(item)))
 
-            bibtex_entry = u',\n    '.join(bibtex_entry)
-            bibtex_entry += u' }\n\n'
+            bibtex_entry = ',\n    '.join(bibtex_entry)
+            bibtex_entry += ' }\n\n'
 
             return bibtex_entry
 
@@ -241,7 +242,7 @@ class BIBTEX(CatalogPlugin):
             # define a function to replace the template entry by its value
             def tpl_replace(objtplname) :
 
-                tpl_field = re.sub(u'[\\{\\}]', u'', objtplname.group())
+                tpl_field = re.sub('[\\{\\}]', '', objtplname.group())
 
                 if tpl_field in TEMPLATE_ALLOWED_FIELDS :
                     if tpl_field in ['pubdate', 'timestamp'] :
@@ -249,26 +250,26 @@ class BIBTEX(CatalogPlugin):
                     elif tpl_field in ['tags', 'authors'] :
                         tpl_field =entry[tpl_field][0]
                     elif tpl_field in ['id', 'series_index'] :
-                        tpl_field = str(entry[tpl_field])
+                        tpl_field = unicode_type(entry[tpl_field])
                     else :
                         tpl_field = entry[tpl_field]
                     return ascii_text(tpl_field)
                 else:
-                    return u''
+                    return ''
 
             if len(template_citation) >0 :
                 tpl_citation = bibtexclass.utf8ToBibtex(
-                    bibtexclass.ValidateCitationKey(re.sub(u'\\{[^{}]*\\}',
+                    bibtexclass.ValidateCitationKey(re.sub('\\{[^{}]*\\}',
                         tpl_replace, template_citation)))
 
                 if len(tpl_citation) >0 :
                     return tpl_citation
 
             if len(entry["isbn"]) > 0 :
-                template_citation = u'%s' % re.sub(u'[\\D]',u'', entry["isbn"])
+                template_citation = '%s' % re.sub('[\\D]','', entry["isbn"])
 
             else :
-                template_citation = u'%s' % str(entry["id"])
+                template_citation = '%s' % unicode_type(entry["id"])
 
             return bibtexclass.ValidateCitationKey(template_citation)
 
@@ -394,8 +395,8 @@ class BIBTEX(CatalogPlugin):
                 for entry in data:
                     entry['ondevice'] = db.catalog_plugin_on_device_temp_mapping[entry['id']]['ondevice']
 
-            outfile.write(u'%%%Calibre catalog\n%%%{0} entries in catalog\n\n'.format(nb_entries))
-            outfile.write(u'@preamble{"This catalog of %d entries was generated by calibre on %s"}\n\n'
+            outfile.write('%%%Calibre catalog\n%%%{0} entries in catalog\n\n'.format(nb_entries))
+            outfile.write('@preamble{"This catalog of %d entries was generated by calibre on %s"}\n\n'
                 % (nb_entries, nowf().strftime("%A, %d. %B %Y %H:%M").decode(preferred_encoding)))
 
             for entry in data:
diff --git a/src/calibre/library/catalogs/csv_xml.py b/src/calibre/library/catalogs/csv_xml.py
index 1267a628ab..382b55ac44 100644
--- a/src/calibre/library/catalogs/csv_xml.py
+++ b/src/calibre/library/catalogs/csv_xml.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__ = 'GPL v3'
 __copyright__ = '2012, Kovid Goyal <kovid@kovidgoyal.net>'
@@ -107,10 +108,10 @@ class CSV_XML(CatalogPlugin):
             outfile = codecs.open(path_to_output, 'w', 'utf8')
 
             # Write a UTF-8 BOM
-            outfile.write(u'\ufeff')
+            outfile.write('\ufeff')
 
             # Output the field headers
-            outfile.write(u'%s\n' % u','.join(fields))
+            outfile.write('%s\n' % ','.join(fields))
 
             # Output the entry fields
             for entry in data:
@@ -144,14 +145,14 @@ class CSV_XML(CatalogPlugin):
                         item = ', '.join(item)
                     elif field == 'isbn':
                         # Could be 9, 10 or 13 digits, with hyphens, possibly ending in 'X'
-                        item = u'%s' % re.sub(r'[^\dX-]', '', item)
+                        item = '%s' % re.sub(r'[^\dX-]', '', item)
                     elif fm.get(field, {}).get('datatype') == 'datetime':
                         item = isoformat(item, as_utc=False)
                     elif field == 'comments':
-                        item = item.replace(u'\r\n', u' ')
-                        item = item.replace(u'\n', u' ')
+                        item = item.replace('\r\n', ' ')
+                        item = item.replace('\n', ' ')
                     elif fm.get(field, {}).get('datatype', None) == 'rating' and item:
-                        item = u'%.2g' % (item / 2.0)
+                        item = '%.2g' % (item / 2)
 
                     # Convert HTML to markdown text
                     if isinstance(item, unicode_type):
@@ -161,9 +162,9 @@ class CSV_XML(CatalogPlugin):
                             if closing_tag:
                                 item = html2text(item)
 
-                    outstr.append(u'"%s"' % unicode_type(item).replace('"', '""'))
+                    outstr.append('"%s"' % unicode_type(item).replace('"', '""'))
 
-                outfile.write(u','.join(outstr) + u'\n')
+                outfile.write(','.join(outstr) + '\n')
             outfile.close()
 
         elif self.fmt == 'xml':
@@ -191,7 +192,7 @@ class CSV_XML(CatalogPlugin):
                         if not isinstance(val, (bytes, unicode_type)):
                             if (fm.get(field, {}).get('datatype', None) ==
                                     'rating' and val):
-                                val = u'%.2g' % (val / 2.0)
+                                val = '%.2g' % (val / 2)
                             val = unicode_type(val)
                         item = getattr(E, field)(val)
                         record.append(item)
@@ -221,7 +222,7 @@ class CSV_XML(CatalogPlugin):
 
                 if 'series' in fields and r['series']:
                     record.append(E.series(r['series'],
-                        index=str(r['series_index'])))
+                        index=unicode_type(r['series_index'])))
 
                 if 'cover' in fields and r['cover']:
                     record.append(E.cover(r['cover'].replace(os.sep, '/')))
diff --git a/src/calibre/library/catalogs/epub_mobi.py b/src/calibre/library/catalogs/epub_mobi.py
index cbe65380fa..112e7c91b7 100644
--- a/src/calibre/library/catalogs/epub_mobi.py
+++ b/src/calibre/library/catalogs/epub_mobi.py
@@ -16,6 +16,7 @@ from calibre.library import current_library_name
 from calibre.library.catalogs import AuthorSortMismatchException, EmptyCatalogException
 from calibre.ptempfile import PersistentTemporaryFile
 from calibre.utils.localization import calibre_langcode_to_name, canonicalize_lang, get_lang
+from polyglot.builtins import unicode_type
 
 Option = namedtuple('Option', 'option, default, dest, action, help')
 
@@ -60,7 +61,7 @@ class EPUB_MOBI(CatalogPlugin):
                            "Default: '%default'\n"
                            "Applies to: AZW3, EPUB, MOBI output formats")),
                    Option('--exclude-genre',
-                          default='\\[.+\\]|^\\+$',
+                          default=r'\[.+\]|^\+$',
                           dest='exclude_genre',
                           action=None,
                           help=_("Regex describing tags to exclude as genres.\n"
@@ -264,7 +265,7 @@ class EPUB_MOBI(CatalogPlugin):
 
         build_log = []
 
-        build_log.append(u"%s('%s'): Generating %s %sin %s environment, locale: '%s'" %
+        build_log.append("%s('%s'): Generating %s %sin %s environment, locale: '%s'" %
             (self.name,
              current_library_name(),
              self.fmt,
@@ -282,23 +283,23 @@ class EPUB_MOBI(CatalogPlugin):
         if opts.connected_device['is_device_connected'] and \
            opts.connected_device['kind'] == 'device':
             if opts.connected_device['serial']:
-                build_log.append(u" connected_device: '%s' #%s%s " %
+                build_log.append(" connected_device: '%s' #%s%s " %
                     (opts.connected_device['name'],
                      opts.connected_device['serial'][0:4],
                      'x' * (len(opts.connected_device['serial']) - 4)))
                 for storage in opts.connected_device['storage']:
                     if storage:
-                        build_log.append(u"  mount point: %s" % storage)
+                        build_log.append("  mount point: %s" % storage)
             else:
-                build_log.append(u" connected_device: '%s'" % opts.connected_device['name'])
+                build_log.append(" connected_device: '%s'" % opts.connected_device['name'])
                 try:
                     for storage in opts.connected_device['storage']:
                         if storage:
-                            build_log.append(u"  mount point: %s" % storage)
+                            build_log.append("  mount point: %s" % storage)
                 except:
-                    build_log.append(u"  (no mount points)")
+                    build_log.append("  (no mount points)")
         else:
-            build_log.append(u" connected_device: '%s'" % opts.connected_device['name'])
+            build_log.append(" connected_device: '%s'" % opts.connected_device['name'])
 
         opts_dict = vars(opts)
         if opts_dict['ids']:
@@ -337,7 +338,7 @@ class EPUB_MOBI(CatalogPlugin):
             sections_list.insert(0, 'Authors')
             opts.generate_authors = True
 
-        opts.log(u" Sections: %s" % ', '.join(sections_list))
+        opts.log(" Sections: %s" % ', '.join(sections_list))
         opts.section_list = sections_list
 
         # Limit thumb_width to 1.0" - 2.0"
@@ -397,7 +398,7 @@ class EPUB_MOBI(CatalogPlugin):
 
         if opts.verbose:
             log.info(" Begin catalog source generation (%s)" %
-                     str(datetime.timedelta(seconds=int(time.time() - opts.start_time))))
+                     unicode_type(datetime.timedelta(seconds=int(time.time() - opts.start_time))))
 
         # Launch the Catalog builder
         catalog = CatalogBuilder(db, opts, self, report_progress=notification)
@@ -406,7 +407,7 @@ class EPUB_MOBI(CatalogPlugin):
             catalog.build_sources()
             if opts.verbose:
                 log.info(" Completed catalog source generation (%s)\n"  %
-                         str(datetime.timedelta(seconds=int(time.time() - opts.start_time))))
+                         unicode_type(datetime.timedelta(seconds=int(time.time() - opts.start_time))))
         except (AuthorSortMismatchException, EmptyCatalogException) as e:
             log.error(" *** Terminated catalog generation: %s ***" % e)
         except:
@@ -499,7 +500,7 @@ class EPUB_MOBI(CatalogPlugin):
 
             if opts.verbose:
                 log.info(" Catalog creation complete (%s)\n" %
-                     str(datetime.timedelta(seconds=int(time.time() - opts.start_time))))
+                     unicode_type(datetime.timedelta(seconds=int(time.time() - opts.start_time))))
 
         # returns to gui2.actions.catalog:catalog_generated()
         return catalog.error
diff --git a/src/calibre/library/catalogs/epub_mobi_builder.py b/src/calibre/library/catalogs/epub_mobi_builder.py
index b629718bcf..a12db3641f 100644
--- a/src/calibre/library/catalogs/epub_mobi_builder.py
+++ b/src/calibre/library/catalogs/epub_mobi_builder.py
@@ -1,8 +1,7 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2010, Greg Riker
-
-from __future__ import print_function
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 import datetime
 import os
@@ -44,7 +43,7 @@ from calibre.utils.localization import get_lang, lang_as_iso639_1
 from calibre.utils.zipfile import ZipFile
 from polyglot.builtins import unicode_type, iteritems, map, zip
 
-NBSP = u'\u00a0'
+NBSP = '\u00a0'
 
 
 class Formatter(TemplateFormatter):
@@ -241,7 +240,7 @@ class CatalogBuilder(object):
             index = book['series_index']
             integer = int(index)
             fraction = index - integer
-            series_index = '%04d%s' % (integer, str('%0.4f' % fraction).lstrip('0'))
+            series_index = '%04d%s' % (integer, unicode_type('%0.4f' % fraction).lstrip('0'))
             key = '%s ~%s %s' % (self._kf_author_to_author_sort(book['author']),
                                     self.generate_sort_title(book['series']),
                                     series_index)
@@ -260,15 +259,15 @@ class CatalogBuilder(object):
          (str): sort key
         """
         if not book['series']:
-            fs = u'{:<%d}!{!s}' % longest_author_sort
+            fs = '{:<%d}!{!s}' % longest_author_sort
             key = fs.format(capitalize(book['author_sort']),
                             capitalize(book['title_sort']))
         else:
             index = book['series_index']
             integer = int(index)
             fraction = index - integer
-            series_index = u'%04d%s' % (integer, str(u'%0.4f' % fraction).lstrip(u'0'))
-            fs = u'{:<%d}~{!s}{!s}' % longest_author_sort
+            series_index = '%04d%s' % (integer, unicode_type('%0.4f' % fraction).lstrip('0'))
+            fs = '{:<%d}~{!s}{!s}' % longest_author_sort
             key = fs.format(capitalize(book['author_sort']),
                             self.generate_sort_title(book['series']),
                             series_index)
@@ -278,7 +277,7 @@ class CatalogBuilder(object):
         index = book['series_index']
         integer = int(index)
         fraction = index - integer
-        series_index = '%04d%s' % (integer, str('%0.4f' % fraction).lstrip('0'))
+        series_index = '%04d%s' % (integer, unicode_type('%0.4f' % fraction).lstrip('0'))
         key = '%s %s' % (self.generate_sort_title(book['series']),
                          series_index)
         return key
@@ -677,9 +676,9 @@ class CatalogBuilder(object):
         # Hack to force the cataloged leading letter to be
         # an unadorned character if the accented version sorts before the unaccented
         exceptions = {
-                        u'Ä':   u'A',
-                        u'Ö':   u'O',
-                        u'Ü':   u'U'
+                        'Ä':   'A',
+                        'Ö':   'O',
+                        'Ü':   'U'
                      }
 
         if key is not None:
@@ -699,7 +698,7 @@ class CatalogBuilder(object):
                 # Hackhackhackhackhack
                 # icu returns bogus results with curly apostrophes, maybe others under OS X 10.6.x
                 # When we see the magic combo of 0/-1 for ordnum/ordlen, special case the logic
-                last_c = u''
+                last_c = ''
                 if ordnum == 0 and ordlen == -1:
                     if icu_upper(c[0]) != last_c:
                         last_c = icu_upper(c[0])
@@ -955,7 +954,7 @@ class CatalogBuilder(object):
             if is_date_undefined(record['pubdate']):
                 this_title['date'] = None
             else:
-                this_title['date'] = strftime(u'%B %Y', as_local_time(record['pubdate']).timetuple())
+                this_title['date'] = strftime('%B %Y', as_local_time(record['pubdate']).timetuple())
 
             this_title['timestamp'] = record['timestamp']
 
@@ -1091,11 +1090,11 @@ class CatalogBuilder(object):
         from calibre.devices.kindle.bookmark import Bookmark
         from calibre.ebooks.metadata import MetaInformation
 
-        MBP_FORMATS = [u'azw', u'mobi', u'prc', u'txt']
+        MBP_FORMATS = ['azw', 'mobi', 'prc', 'txt']
         mbp_formats = set(MBP_FORMATS)
-        PDR_FORMATS = [u'pdf']
+        PDR_FORMATS = ['pdf']
         pdr_formats = set(PDR_FORMATS)
-        TAN_FORMATS = [u'tpz', u'azw1']
+        TAN_FORMATS = ['tpz', 'azw1']
         tan_formats = set(TAN_FORMATS)
 
         class BookmarkDevice(Device):
@@ -1174,7 +1173,7 @@ class CatalogBuilder(object):
                             book['percent_read'] = min(float(100 * myBookmark.last_read / myBookmark.book_length), 100)
                         except:
                             book['percent_read'] = 0
-                        dots = int((book['percent_read'] + 5) / 10)
+                        dots = int((book['percent_read'] + 5) // 10)
                         dot_string = self.SYMBOL_PROGRESS_READ * dots
                         empty_dots = self.SYMBOL_PROGRESS_UNREAD * (10 - dots)
                         book['reading_progress'] = '%s%s' % (dot_string, empty_dots)
@@ -1411,7 +1410,7 @@ class CatalogBuilder(object):
         Return:
          (dict): formatted args for templating
         """
-        series_index = str(book['series_index'])
+        series_index = unicode_type(book['series_index'])
         if series_index.endswith('.0'):
             series_index = series_index[:-2]
         args = dict(
@@ -1661,7 +1660,7 @@ class CatalogBuilder(object):
                     key=lambda x: sort_key(self._kf_books_by_author_sorter_author_sort(x, len(las))))
 
                 # Create a new month anchor
-                date_string = strftime(u'%B %Y', current_date.timetuple())
+                date_string = strftime('%B %Y', current_date.timetuple())
                 pIndexTag = soup.new_tag("p")
                 pIndexTag['class'] = "date_index"
                 aTag = soup.new_tag("a")
@@ -1919,7 +1918,7 @@ class CatalogBuilder(object):
         def _add_books_to_html_by_day(todays_list, dtc):
             if len(todays_list):
                 # Create a new day anchor
-                date_string = strftime(u'%A, %B %d', current_date.timetuple())
+                date_string = strftime('%A, %B %d', current_date.timetuple())
                 pIndexTag = soup.new_tag("p")
                 pIndexTag['class'] = "date_index"
                 aTag = soup.new_tag("a")
@@ -1981,7 +1980,7 @@ class CatalogBuilder(object):
                     ptc = 0
 
                     # Percent read
-                    dots = int((new_entry['percent_read'] + 5) / 10)
+                    dots = int((new_entry['percent_read'] + 5) // 10)
                     dot_string = self.SYMBOL_PROGRESS_READ * dots
                     empty_dots = self.SYMBOL_PROGRESS_UNREAD * (10 - dots)
                     pBookTag.insert(ptc, NavigableString('%s%s' % (dot_string, empty_dots)))
@@ -2690,7 +2689,7 @@ class CatalogBuilder(object):
         series_index = ''
         if book['series']:
             series = book['series']
-            series_index = str(book['series_index'])
+            series_index = unicode_type(book['series_index'])
             if series_index.endswith('.0'):
                 series_index = series_index[:-2]
 
@@ -2754,7 +2753,7 @@ class CatalogBuilder(object):
             publisher = book['publisher']
 
         # Rating
-        stars = int(book['rating']) / 2
+        stars = int(book['rating']) // 2
         rating = ''
         if stars:
             star_string = self.SYMBOL_FULL_RATING * stars
@@ -2958,8 +2957,8 @@ class CatalogBuilder(object):
             font = ImageFont.truetype(default_font, 48)
         text = self.opts.catalog_title.encode('utf-8')
         width, height = draw.textsize(text, font=font)
-        left = max(int((MI_WIDTH - width) / 2.), 0)
-        top = max(int((MI_HEIGHT - height) / 2.), 0)
+        left = max(int((MI_WIDTH - width) / 2), 0)
+        top = max(int((MI_HEIGHT - height) / 2), 0)
         draw.text((left, top), text, fill=(0, 0, 0), font=font)
         with open(out_path, 'wb') as f:
             img.save(f, 'GIF')
@@ -3100,7 +3099,7 @@ class CatalogBuilder(object):
             navLabelTag = ncx_soup.new_tag("navLabel")
             textTag = ncx_soup.new_tag("text")
             if book['series']:
-                series_index = str(book['series_index'])
+                series_index = unicode_type(book['series_index'])
                 if series_index.endswith('.0'):
                     series_index = series_index[:-2]
                 if self.generate_for_kindle_mobi:
@@ -3694,7 +3693,7 @@ class CatalogBuilder(object):
         # Add *article* entries for each populated month
         # master_months_list{}: [0]:titles list [1]:date
         for books_by_month in master_month_list:
-            datestr = strftime(u'%B %Y', books_by_month[1].timetuple())
+            datestr = strftime('%B %Y', books_by_month[1].timetuple())
             navPointByMonthTag = ncx_soup.new_tag('navPoint')
             if self.generate_for_kindle_mobi:
                 navPointByMonthTag['class'] = "article"
@@ -3844,7 +3843,7 @@ class CatalogBuilder(object):
         # Add *article* entries for each populated day
         # master_day_list{}: [0]:titles list [1]:date
         for books_by_day in master_day_list:
-            datestr = strftime(u'%A, %B %d', books_by_day[1].timetuple())
+            datestr = strftime('%A, %B %d', books_by_day[1].timetuple())
             navPointByDayTag = ncx_soup.new_tag('navPoint')
             if self.generate_for_kindle_mobi:
                 navPointByDayTag['class'] = "article"
@@ -3995,7 +3994,7 @@ class CatalogBuilder(object):
                     for title in genre['books']:
                         titles.append(title['title'])
                     titles = sorted(titles, key=lambda x: (self.generate_sort_title(x), self.generate_sort_title(x)))
-                    titles_list = self.generate_short_description(u" • ".join(titles), dest="description")
+                    titles_list = self.generate_short_description(" • ".join(titles), dest="description")
                     cmTag.insert(0, NavigableString(self.format_ncx_text(titles_list, dest='description')))
 
                 navPointVolumeTag.insert(3, cmTag)
@@ -4205,7 +4204,7 @@ class CatalogBuilder(object):
         rating = ''
         try:
             if 'rating' in book:
-                stars = int(book['rating']) / 2
+                stars = int(book['rating']) // 2
                 if stars:
                     star_string = self.SYMBOL_FULL_RATING * stars
                     empty_stars = self.SYMBOL_EMPTY_RATING * (5 - stars)
@@ -4489,7 +4488,7 @@ class CatalogBuilder(object):
         Return:
          (str): legal XHTML anchor string of unicode character name
         """
-        fullname = u''.join(unicodedata.name(unicode_type(cc)) for cc in c)
+        fullname = ''.join(unicodedata.name(unicode_type(cc)) for cc in c)
         terms = fullname.split()
         return "_".join(terms)
 
@@ -4521,7 +4520,7 @@ class CatalogBuilder(object):
                 matched = list(set(record['tags']) & set(excluded_tags))
                 if matched:
                     for rule in self.opts.exclusion_rules:
-                        if rule[1] == _('Tags') and rule[2] == str(matched[0]):
+                        if rule[1] == _('Tags') and rule[2] == unicode_type(matched[0]):
                             self.opts.log.info("  - '%s' by %s (Exclusion rule '%s')" %
                                 (record['title'], record['authors'][0], rule[0]))
 
@@ -4808,12 +4807,12 @@ class CatalogBuilder(object):
             self.progress_int = 0.01
         self.reporter(self.progress_int, self.progress_string)
         if self.opts.cli_environment:
-            log_msg = u"%3.0f%% %s" % (self.progress_int * 100, self.progress_string)
+            log_msg = "%3.0f%% %s" % (self.progress_int * 100, self.progress_string)
             if self.opts.verbose:
-                log_msg += " (%s)" % str(datetime.timedelta(seconds=int(time.time() - self.opts.start_time)))
+                log_msg += " (%s)" % unicode_type(datetime.timedelta(seconds=int(time.time() - self.opts.start_time)))
         else:
             log_msg = ("%s (%s)" % (self.progress_string,
-                str(datetime.timedelta(seconds=int(time.time() - self.opts.start_time)))))
+                unicode_type(datetime.timedelta(seconds=int(time.time() - self.opts.start_time)))))
         self.opts.log(log_msg)
 
     def update_progress_micro_step(self, description, micro_step_pct):
diff --git a/src/calibre/library/catalogs/utils.py b/src/calibre/library/catalogs/utils.py
index 09d4ad84bc..593b96cef7 100644
--- a/src/calibre/library/catalogs/utils.py
+++ b/src/calibre/library/catalogs/utils.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import absolute_import, division, print_function, unicode_literals
 
-from __future__ import print_function
 __license__   = 'GPL v3'
 __copyright__ = '2010, Greg Riker'
 __docformat__ = 'restructuredtext en'
@@ -44,7 +44,7 @@ class NumberToText(object):  # {{{
 
         # Build the hundreds component
         if hundredsComponent:
-            hundredsComponentString = "%s hundred" % self.hundreds[hundredsComponent/100]
+            hundredsComponentString = "%s hundred" % self.hundreds[hundredsComponent//100]
         else:
             hundredsComponentString = ""
 
@@ -56,7 +56,7 @@ class NumberToText(object):  # {{{
             onesPart = ""
 
             # Get the tens part
-            tensPart = self.tens[tensComponent / 10]
+            tensPart = self.tens[tensComponent // 10]
             onesPart = self.lessThanTwenty[tensComponent % 10]
 
             if intToTranslate % 10:
@@ -183,8 +183,8 @@ class NumberToText(object):  # {{{
                 self.text = "one billion"
             else :
                 # Isolate the three-digit number groups
-                millionsNumber  = number/10**6
-                thousandsNumber = (number - (millionsNumber * 10**6))/10**3
+                millionsNumber  = number//10**6
+                thousandsNumber = (number - (millionsNumber * 10**6))//10**3
                 hundredsNumber  = number - (millionsNumber * 10**6) - (thousandsNumber * 10**3)
                 if self.verbose:
                     print("Converting %s %s %s" % (millionsNumber, thousandsNumber, hundredsNumber))
@@ -196,7 +196,7 @@ class NumberToText(object):  # {{{
                 # Convert thousandsNumber
                 if thousandsNumber:
                     if number > 1099 and number < 2000:
-                        resultString = '%s %s' % (self.lessThanTwenty[number/100],
+                        resultString = '%s %s' % (self.lessThanTwenty[number//100],
                                                     self.stringFromInt(number % 100))
                         self.text = resultString.strip().capitalize()
                         return
@@ -222,6 +222,6 @@ class NumberToText(object):  # {{{
                     resultString = "zero"
 
                 if self.verbose:
-                    self.log(u'resultString: %s' % resultString)
+                    self.log('resultString: %s' % resultString)
                 self.text = resultString.strip().capitalize()
 # }}}
diff --git a/src/calibre/library/database.py b/src/calibre/library/database.py
index e2fd47390a..01a29e3813 100644
--- a/src/calibre/library/database.py
+++ b/src/calibre/library/database.py
@@ -1,9 +1,12 @@
-from __future__ import print_function
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 __license__   = 'GPL v3'
 __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, sre_constants
 from zlib import compress, decompress
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index c31de99a00..02b348f3e6 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -1,4 +1,5 @@
-from __future__ import with_statement
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net'
 __docformat__ = 'restructuredtext en'
@@ -6,6 +7,7 @@ __docformat__ = 'restructuredtext en'
 '''
 The database used to store ebook metadata
 '''
+
 import os, sys, shutil, glob, time, functools, traceback, re, \
         json, uuid, hashlib, copy, numbers
 from collections import defaultdict, namedtuple
@@ -91,7 +93,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         if self._library_id_ is None:
             ans = self.conn.get('SELECT uuid FROM library_id', all=False)
             if ans is None:
-                ans = str(uuid.uuid4())
+                ans = unicode_type(uuid.uuid4())
                 self.library_id = ans
             else:
                 self._library_id_ = ans
@@ -256,11 +258,11 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             from calibre.library.coloring import migrate_old_rule
             old_rules = []
             for i in range(1, 6):
-                col = self.prefs.get('column_color_name_'+str(i), None)
-                templ = self.prefs.get('column_color_template_'+str(i), None)
+                col = self.prefs.get('column_color_name_'+unicode_type(i), None)
+                templ = self.prefs.get('column_color_template_'+unicode_type(i), None)
                 if col and templ:
                     try:
-                        del self.prefs['column_color_name_'+str(i)]
+                        del self.prefs['column_color_name_'+unicode_type(i)]
                         rules = migrate_old_rule(self.field_metadata, templ)
                         for templ in rules:
                             old_rules.append((col, templ))
@@ -359,7 +361,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         ''')
         self.conn.execute(
             'UPDATE authors SET sort=author_to_author_sort(name) WHERE sort IS NULL')
-        self.conn.executescript(u'''
+        self.conn.executescript('''
             CREATE TEMP VIEW IF NOT EXISTS tag_browser_news AS SELECT DISTINCT
                 id,
                 name,
@@ -372,7 +374,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                         (SELECT id FROM tags WHERE name="{0}")));
             '''.format(_('News')))
 
-        self.conn.executescript(u'''
+        self.conn.executescript('''
             CREATE TEMP VIEW IF NOT EXISTS tag_browser_filtered_news AS SELECT DISTINCT
                 id,
                 name,
@@ -450,7 +452,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                 # account for the series index column. Field_metadata knows that
                 # the series index is one larger than the series. If you change
                 # it here, be sure to change it there as well.
-                self.FIELD_MAP[str(col)+'_index'] = base = base+1
+                self.FIELD_MAP[unicode_type(col)+'_index'] = base = base+1
                 self.field_metadata.set_field_record_index(
                             self.custom_column_num_map[col]['label']+'_index',
                             base,
@@ -487,7 +489,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                 # There is a chance that these can be duplicates of an existing
                 # user category. Print the exception and continue.
                 try:
-                    self.field_metadata.add_user_category(label=u'@' + cat, name=cat)
+                    self.field_metadata.add_user_category(label='@' + cat, name=cat)
                 except:
                     traceback.print_exc()
 
@@ -1127,7 +1129,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             try:
                 quathors = mi.authors[:10]  # Too many authors causes parsing of
                 # the search expression to fail
-                query = u' and '.join([u'author:"=%s"'%(a.replace('"', '')) for a in
+                query = ' and '.join(['author:"=%s"'%(a.replace('"', '')) for a in
                     quathors])
                 qauthors = mi.authors[10:]
             except ValueError:
@@ -1747,7 +1749,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             self.id = id
 
         def __unicode_representation__(self):
-            return u'n=%s s=%s c=%d rt=%d rc=%d id=%s' % (
+            return 'n=%s s=%s c=%d rt=%d rc=%d id=%s' % (
                 self.n, self.s, self.c, self.rt, self.rc, self.id)
 
         if ispy3:
@@ -1977,7 +1979,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             # Duplicate the build of items below to avoid using a lambda func
             # in the main Tag loop. Saves a few %
             if datatype == 'rating':
-                formatter = (lambda x:u'\u2605'*int(x/2))
+                formatter = (lambda x:'\u2605'*int(x//2))
                 avgr = lambda x: x.n
                 # eliminate the zero ratings line as well as count == 0
                 items = [v for v in tcategories[category].values() if v.c > 0 and v.n != 0]
@@ -2613,7 +2615,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         if commit:
             self.conn.commit()
         self.data.set(book_id, self.FIELD_MAP['languages'],
-                u','.join(final_languages), row_is_id=True)
+                ','.join(final_languages), row_is_id=True)
         if notify:
             self.notify('metadata', [book_id])
         return books_to_refresh
@@ -2992,7 +2994,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         tags = [x.strip().replace(',', ';') for x in tags if x.strip()]
         tags = [x.decode(preferred_encoding, 'replace')
                     if isbytestring(x) else x for x in tags]
-        tags = [u' '.join(x.split()) for x in tags]
+        tags = [' '.join(x.split()) for x in tags]
         ans, seen = [], set()
         for tag in tags:
             if tag.lower() not in seen:
@@ -3068,7 +3070,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         self.conn.commit()
 
         for x in ids:
-            tags = u','.join(self.get_tags(x))
+            tags = ','.join(self.get_tags(x))
             self.data.set(x, self.FIELD_MAP['tags'], tags, row_is_id=True)
         if notify:
             self.notify('metadata', ids)
@@ -3124,7 +3126,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         self.dirtied({id}|books_to_refresh, commit=False)
         if commit:
             self.conn.commit()
-        tags = u','.join(self.get_tags(id))
+        tags = ','.join(self.get_tags(id))
         self.data.set(id, self.FIELD_MAP['tags'], tags, row_is_id=True)
         if notify:
             self.notify('metadata', [id])
@@ -3178,7 +3180,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             if not isinstance(series, unicode_type):
                 series = series.decode(preferred_encoding, 'replace')
             series = series.strip()
-            series = u' '.join(series.split())
+            series = ' '.join(series.split())
             sx = self.conn.get('SELECT id,name from series WHERE name=?', (series,))
             if sx:
                 aid, cur_name = sx[0]
diff --git a/src/calibre/library/restore.py b/src/calibre/library/restore.py
index 47df5d20a4..026c9526df 100644
--- a/src/calibre/library/restore.py
+++ b/src/calibre/library/restore.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
diff --git a/src/calibre/library/save_to_disk.py b/src/calibre/library/save_to_disk.py
index 338903af0b..a5640c7484 100644
--- a/src/calibre/library/save_to_disk.py
+++ b/src/calibre/library/save_to_disk.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
-from __future__ import with_statement
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
@@ -217,7 +217,7 @@ def get_components(template, mi, id, timefmt='%b %Y', length=250,
     if hasattr(mi, 'last_modified') and hasattr(mi.last_modified, 'timetuple'):
         format_args['last_modified'] = strftime(timefmt, mi.last_modified.timetuple())
 
-    format_args['id'] = str(id)
+    format_args['id'] = unicode_type(id)
     # Now format the custom fields
     custom_metadata = mi.get_all_user_metadata(make_copy=False)
     for key in custom_metadata:
@@ -247,7 +247,7 @@ def get_components(template, mi, id, timefmt='%b %Y', length=250,
     components = [x.strip() for x in components.split('/')]
     components = [sanitize_func(x) for x in components if x]
     if not components:
-        components = [str(id)]
+        components = [unicode_type(id)]
     if to_lowercase:
         components = [x.lower() for x in components]
     if replace_whitespace:
@@ -360,7 +360,7 @@ def do_save_book_to_disk(db, book_id, mi, plugboards,
         return not formats_written, book_id, mi.title
 
     for fmt in formats:
-        fmt_path = base_path+'.'+str(fmt)
+        fmt_path = base_path+'.'+unicode_type(fmt)
         try:
             db.copy_format_to(book_id, fmt, fmt_path)
             formats_written = True
diff --git a/src/calibre/library/schema_upgrades.py b/src/calibre/library/schema_upgrades.py
index 47045156ef..785ddf0663 100644
--- a/src/calibre/library/schema_upgrades.py
+++ b/src/calibre/library/schema_upgrades.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
-from __future__ import print_function, with_statement
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
@@ -593,7 +593,7 @@ class SchemaUpgrade(object):
                 existing = frozenset(map(int, custom_recipes))
                 if id_ in existing:
                     id_ = max(existing) + 1000
-                id_ = str(id_)
+                id_ = unicode_type(id_)
                 fname = custom_recipe_filename(id_, title)
                 custom_recipes[id_] = (title, fname)
                 if isinstance(script, unicode_type):
diff --git a/src/calibre/library/sqlite.py b/src/calibre/library/sqlite.py
index 95ad9c2898..b237b013ff 100644
--- a/src/calibre/library/sqlite.py
+++ b/src/calibre/library/sqlite.py
@@ -1,4 +1,5 @@
-from __future__ import print_function, with_statement
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net'
 __docformat__ = 'restructuredtext en'
@@ -7,6 +8,7 @@ __docformat__ = 'restructuredtext en'
 Wrapper for multi-threaded access to a single sqlite database connection. Serializes
 all calls.
 '''
+
 import sqlite3 as sqlite, traceback, time, uuid, os
 from sqlite3 import IntegrityError, OperationalError
 from threading import Thread
@@ -20,7 +22,7 @@ from calibre import isbytestring, force_unicode
 from calibre.constants import iswindows, DEBUG, plugins, plugins_loc
 from calibre.utils.icu import sort_key
 from calibre import prints
-from polyglot.builtins import unicode_type, cmp
+from polyglot.builtins import cmp, native_string_type, unicode_type
 from polyglot import reprlib
 from polyglot.queue import Queue
 
@@ -78,7 +80,7 @@ def adapt_datetime(dt):
 
 
 sqlite.register_adapter(datetime, adapt_datetime)
-sqlite.register_converter('timestamp', convert_timestamp)
+sqlite.register_converter(native_string_type('timestamp'), convert_timestamp)
 
 
 def convert_bool(val):
@@ -86,8 +88,8 @@ def convert_bool(val):
 
 
 sqlite.register_adapter(bool, lambda x : 1 if x else 0)
-sqlite.register_converter('bool', convert_bool)
-sqlite.register_converter('BOOL', convert_bool)
+sqlite.register_converter(native_string_type('bool'), convert_bool)
+sqlite.register_converter(native_string_type('BOOL'), convert_bool)
 
 
 class DynamicFilter(object):
@@ -162,7 +164,7 @@ class IdentifiersConcat(object):
         self.ans = []
 
     def step(self, key, val):
-        self.ans.append(u'%s:%s'%(key, val))
+        self.ans.append('%s:%s'%(key, val))
 
     def finalize(self):
         try:
@@ -262,15 +264,15 @@ def do_connect(path, row_factory=None):
     conn.row_factory = sqlite.Row if row_factory else (lambda cursor, row : list(row))
     conn.create_aggregate('concat', 1, Concatenate)
     conn.create_aggregate('aum_sortconcat', 4, AumSortedConcatenate)
-    conn.create_collation('PYNOCASE', partial(pynocase,
+    conn.create_collation(native_string_type('PYNOCASE'), partial(pynocase,
         encoding=encoding))
     conn.create_function('title_sort', 1, title_sort)
     conn.create_function('author_to_author_sort', 1,
             _author_to_author_sort)
-    conn.create_function('uuid4', 0, lambda : str(uuid.uuid4()))
+    conn.create_function('uuid4', 0, lambda : unicode_type(uuid.uuid4()))
     # Dummy functions for dynamically created filters
     conn.create_function('books_list_filter', 1, lambda x: 1)
-    conn.create_collation('icucollate', icu_collator)
+    conn.create_collation(native_string_type('icucollate'), icu_collator)
     return conn
 
 
@@ -320,7 +322,7 @@ class DBThread(Thread):
                                 break
                             except OperationalError as err:
                                 # Retry if unable to open db file
-                                e = str(err)
+                                e = unicode_type(err)
                                 if 'unable to open' not in e or i == 2:
                                     if 'unable to open' in e:
                                         prints('Unable to open database for func',