diff --git a/src/calibre/customize/zipplugin.py b/src/calibre/customize/zipplugin.py
index fec7842afd..a079d53744 100644
--- a/src/calibre/customize/zipplugin.py
+++ b/src/calibre/customize/zipplugin.py
@@ -14,8 +14,8 @@ from functools import partial
 from calibre import as_unicode
 from calibre.customize import (Plugin, numeric_version, platform,
         InvalidPlugin, PluginNotFound)
-from polyglot.builtins import (itervalues, iterkeys, map,
-        string_or_bytes, unicode_type)
+from polyglot.builtins import (itervalues, map, string_or_bytes,
+        unicode_type)
 
 # PEP 302 based plugin loading mechanism, works around the bug in zipimport in
 # python 2.x that prevents importing from zip files in locations whose paths
@@ -281,7 +281,7 @@ class PluginLoader(object):
 
         # Legacy plugins
         if '__init__' not in names:
-            for name in list(iterkeys(names)):
+            for name in tuple(names):
                 if '.' not in name and name.endswith('plugin'):
                     names['__init__'] = names[name]
                     break
diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index ba9e696ce5..cc39b7f0a8 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -12,7 +12,7 @@ import os, shutil, uuid, json, glob, time, hashlib, errno, sys
 from functools import partial
 
 import apsw
-from polyglot.builtins import (iteritems, iterkeys, itervalues,
+from polyglot.builtins import (iteritems, itervalues,
         unicode_type, reraise, string_or_bytes)
 
 from calibre import isbytestring, force_unicode, prints, as_unicode
@@ -223,7 +223,7 @@ def SortedConcatenate(sep=','):
     def finalize(ctxt):
         if len(ctxt) == 0:
             return None
-        return sep.join(map(ctxt.get, sorted(iterkeys(ctxt))))
+        return sep.join(map(ctxt.get, sorted(ctxt)))
 
     return ({}, step, finalize)
 
@@ -248,7 +248,7 @@ def AumSortedConcatenate():
             ctxt[ndx] = ':::'.join((author, sort, link))
 
     def finalize(ctxt):
-        keys = list(iterkeys(ctxt))
+        keys = list(ctxt)
         l = len(keys)
         if l == 0:
             return None
@@ -734,7 +734,7 @@ class DB(object):
         }
 
         # Create Tag Browser categories for custom columns
-        for k in sorted(iterkeys(self.custom_column_label_map)):
+        for k in sorted(self.custom_column_label_map):
             v = self.custom_column_label_map[k]
             if v['normalized']:
                 is_category = True
diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index f04f16edeb..1a408939df 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -11,7 +11,7 @@ import os, traceback, random, shutil, operator
 from io import BytesIO
 from collections import defaultdict, Set, MutableSet
 from functools import wraps, partial
-from polyglot.builtins import iteritems, iterkeys, itervalues, unicode_type, zip, string_or_bytes
+from polyglot.builtins import iteritems, itervalues, unicode_type, zip, string_or_bytes
 from time import time
 
 from calibre import isbytestring, as_unicode
@@ -170,7 +170,7 @@ class Cache(object):
         # Reconstruct the user categories, putting them into field_metadata
         fm = self.field_metadata
         fm.remove_dynamic_categories()
-        for user_cat in sorted(iterkeys(self._pref('user_categories', {})), key=sort_key):
+        for user_cat in sorted(self._pref('user_categories', {}), key=sort_key):
             cat_name = '@' + user_cat  # add the '@' to avoid name collision
             while cat_name:
                 try:
@@ -181,7 +181,7 @@ class Cache(object):
 
         # add grouped search term user categories
         muc = frozenset(self._pref('grouped_search_make_user_categories', []))
-        for cat in sorted(iterkeys(self._pref('grouped_search_terms', {})), key=sort_key):
+        for cat in sorted(self._pref('grouped_search_terms', {}), key=sort_key):
             if cat in muc:
                 # There is a chance that these can be duplicates of an existing
                 # user category. Print the exception and continue.
@@ -1117,7 +1117,7 @@ class Cache(object):
     @read_api
     def get_a_dirtied_book(self):
         if self.dirtied_cache:
-            return random.choice(tuple(iterkeys(self.dirtied_cache)))
+            return random.choice(tuple(self.dirtied_cache))
         return None
 
     @read_api
@@ -1339,7 +1339,7 @@ class Cache(object):
 
                 user_mi = mi.get_all_user_metadata(make_copy=False)
                 fm = self.field_metadata
-                for key in iterkeys(user_mi):
+                for key in user_mi:
                     if (key in fm and user_mi[key]['datatype'] == fm[key]['datatype'] and (
                         user_mi[key]['datatype'] != 'text' or (
                             user_mi[key]['is_multiple'] == fm[key]['is_multiple']))):
@@ -1458,7 +1458,7 @@ class Cache(object):
 
         size_map = table.remove_formats(formats_map, self.backend)
         self.fields['size'].table.update_sizes(size_map)
-        self._update_last_modified(tuple(iterkeys(formats_map)))
+        self._update_last_modified(tuple(formats_map))
 
     @read_api
     def get_next_series_num_for(self, series, field='series', current_indices=False):
diff --git a/src/calibre/db/categories.py b/src/calibre/db/categories.py
index 38489a40fb..cc6ea00dd8 100644
--- a/src/calibre/db/categories.py
+++ b/src/calibre/db/categories.py
@@ -9,7 +9,7 @@ __docformat__ = 'restructuredtext en'
 
 import copy
 from functools import partial
-from polyglot.builtins import iteritems, iterkeys, unicode_type, map
+from polyglot.builtins import iteritems, unicode_type, map
 
 from calibre.constants import ispy3
 from calibre.ebooks.metadata import author_to_author_sort
@@ -219,7 +219,7 @@ def get_categories(dbcache, sort='name', book_ids=None, first_letter_sort=False)
             taglist[c] = dict(map(lambda t:(icu_lower(t.name), t), items))
 
         # Add the category values to the user categories
-        for user_cat in sorted(iterkeys(user_categories), key=sort_key):
+        for user_cat in sorted(user_categories, key=sort_key):
             items = []
             names_seen = {}
             user_cat_is_gst = user_cat in gst
diff --git a/src/calibre/db/fields.py b/src/calibre/db/fields.py
index d42ab52db9..f7e699ef1a 100644
--- a/src/calibre/db/fields.py
+++ b/src/calibre/db/fields.py
@@ -19,7 +19,7 @@ from calibre.utils.config_base import tweaks
 from calibre.utils.icu import sort_key
 from calibre.utils.date import UNDEFINED_DATE, clean_date_for_sort, parse_date
 from calibre.utils.localization import calibre_langcode_to_name
-from polyglot.builtins import iteritems, iterkeys
+from polyglot.builtins import iteritems
 
 
 def bool_sort_key(bools_are_tristate):
@@ -184,7 +184,7 @@ class OneToOneField(Field):
         return {item_id}
 
     def __iter__(self):
-        return iterkeys(self.table.book_col_map)
+        return iter(self.table.book_col_map)
 
     def sort_keys_for_books(self, get_metadata, lang_map):
         bcmg = self.table.book_col_map.get
@@ -456,7 +456,7 @@ class ManyToOneField(Field):
         return self.table.col_book_map.get(item_id, set())
 
     def __iter__(self):
-        return iterkeys(self.table.id_map)
+        return iter(self.table.id_map)
 
     def sort_keys_for_books(self, get_metadata, lang_map):
         sk_map = LazySortMap(self._default_sort_key, self._sort_key, self.table.id_map)
@@ -507,7 +507,7 @@ class ManyToManyField(Field):
         return self.table.col_book_map.get(item_id, set())
 
     def __iter__(self):
-        return iterkeys(self.table.id_map)
+        return iter(self.table.id_map)
 
     def sort_keys_for_books(self, get_metadata, lang_map):
         sk_map = LazySortMap(self._default_sort_key, self._sort_key, self.table.id_map)
@@ -561,7 +561,7 @@ class IdentifiersField(ManyToManyField):
         'Sort by identifier keys'
         bcmg = self.table.book_col_map.get
         dv = {self._default_sort_key:None}
-        return lambda book_id: tuple(sorted(iterkeys(bcmg(book_id, dv))))
+        return lambda book_id: tuple(sorted(bcmg(book_id, dv)))
 
     def iter_searchable_values(self, get_metadata, candidates, default_value=()):
         bcm = self.table.book_col_map
diff --git a/src/calibre/db/lazy.py b/src/calibre/db/lazy.py
index e3c5128ed4..e200b86b97 100644
--- a/src/calibre/db/lazy.py
+++ b/src/calibre/db/lazy.py
@@ -15,7 +15,7 @@ from copy import deepcopy
 from calibre.ebooks.metadata.book.base import Metadata, SIMPLE_GET, TOP_LEVEL_IDENTIFIERS, NULL_VALUES, ALL_METADATA_FIELDS
 from calibre.ebooks.metadata.book.formatter import SafeFormat
 from calibre.utils.date import utcnow
-from polyglot.builtins import iterkeys, unicode_type
+from polyglot.builtins import unicode_type
 
 # Lazy format metadata retrieval {{{
 '''
@@ -393,7 +393,7 @@ class ProxyMetadata(Metadata):
 
     def all_field_keys(self):
         um = ga(self, '_user_metadata')
-        return frozenset(ALL_METADATA_FIELDS.union(iterkeys(um)))
+        return frozenset(ALL_METADATA_FIELDS.union(frozenset(um)))
 
     @property
     def _proxy_metadata(self):
diff --git a/src/calibre/db/schema_upgrades.py b/src/calibre/db/schema_upgrades.py
index 7b5dc28832..d9859b366a 100644
--- a/src/calibre/db/schema_upgrades.py
+++ b/src/calibre/db/schema_upgrades.py
@@ -11,7 +11,7 @@ import os
 
 from calibre import prints
 from calibre.utils.date import isoformat, DEFAULT_DATE
-from polyglot.builtins import iterkeys, itervalues, unicode_type
+from polyglot.builtins import itervalues, unicode_type
 
 
 class SchemaUpgrade(object):
@@ -596,7 +596,7 @@ class SchemaUpgrade(object):
                     custom_recipe_filename)
             bdir = os.path.dirname(custom_recipes.file_path)
             for id_, title, script in recipes:
-                existing = frozenset(map(int, iterkeys(custom_recipes)))
+                existing = frozenset(map(int, custom_recipes))
                 if id_ in existing:
                     id_ = max(existing) + 1000
                 id_ = str(id_)
diff --git a/src/calibre/db/search.py b/src/calibre/db/search.py
index b4cea09c71..19b9b00109 100644
--- a/src/calibre/db/search.py
+++ b/src/calibre/db/search.py
@@ -19,7 +19,7 @@ from calibre.utils.date import parse_date, UNDEFINED_DATE, now, dt_as_local
 from calibre.utils.icu import primary_contains, sort_key
 from calibre.utils.localization import lang_map, canonicalize_lang
 from calibre.utils.search_query_parser import SearchQueryParser, ParseException
-from polyglot.builtins import iteritems, iterkeys, unicode_type, string_or_bytes
+from polyglot.builtins import iteritems, unicode_type, string_or_bytes
 
 CONTAINS_MATCH = 0
 EQUALS_MATCH   = 1
@@ -445,7 +445,7 @@ class SavedSearchQueries(object):  # {{{
             db._set_pref(self.opt_name, smap)
 
     def names(self):
-        return sorted(iterkeys(self.queries), key=sort_key)
+        return sorted(self.queries, key=sort_key)
 # }}}
 
 
diff --git a/src/calibre/db/tests/filesystem.py b/src/calibre/db/tests/filesystem.py
index 11c9fbe0d7..aac9480b0a 100644
--- a/src/calibre/db/tests/filesystem.py
+++ b/src/calibre/db/tests/filesystem.py
@@ -13,7 +13,6 @@ from io import BytesIO
 from calibre.constants import iswindows
 from calibre.db.tests.base import BaseTest
 from calibre.ptempfile import TemporaryDirectory
-from polyglot.builtins import iterkeys
 
 
 class FilesystemTest(BaseTest):
@@ -56,7 +55,7 @@ class FilesystemTest(BaseTest):
         cache2 = self.init_cache(cl)
         for c in (cache, cache2):
             data = self.get_filesystem_data(c, 1)
-            ae(set(iterkeys(orig_data)), set(iterkeys(data)))
+            ae(set(orig_data), set(data))
             ae(orig_data, data, 'Filesystem data does not match')
             ae(c.field_for('path', 1), 'Moved/Moved (1)')
             ae(c.field_for('path', 3), 'Moved1/Moved1 (3)')
diff --git a/src/calibre/db/tests/legacy.py b/src/calibre/db/tests/legacy.py
index 9310392882..b0f88feb30 100644
--- a/src/calibre/db/tests/legacy.py
+++ b/src/calibre/db/tests/legacy.py
@@ -14,7 +14,7 @@ from operator import itemgetter
 
 from calibre.library.field_metadata import fm_as_dict
 from calibre.db.tests.base import BaseTest
-from polyglot.builtins import iteritems, iterkeys, range
+from polyglot.builtins import iteritems, range
 
 # Utils {{{
 
@@ -316,9 +316,9 @@ class LegacyTest(BaseTest):
         db = self.init_old()
         cache = ndb.new_api
         tmap = cache.get_id_map('tags')
-        t = next(iterkeys(tmap))
+        t = next(iter(tmap))
         pmap = cache.get_id_map('publisher')
-        p = next(iterkeys(pmap))
+        p = next(iter(pmap))
         run_funcs(self, db, ndb, (
             ('delete_tag_using_id', t),
             ('delete_publisher_using_id', p),
diff --git a/src/calibre/db/tests/reading.py b/src/calibre/db/tests/reading.py
index 3b90b4d93d..5c0a138d61 100644
--- a/src/calibre/db/tests/reading.py
+++ b/src/calibre/db/tests/reading.py
@@ -13,7 +13,7 @@ from time import time
 
 from calibre.utils.date import utc_tz
 from calibre.db.tests.base import BaseTest
-from polyglot.builtins import iteritems, iterkeys, itervalues, range
+from polyglot.builtins import iteritems, itervalues, range
 
 
 class ReadingTest(BaseTest):
@@ -439,7 +439,7 @@ class ReadingTest(BaseTest):
         'Test getting the author sort for authors from the db'
         cache = self.init_cache()
         table = cache.fields['authors'].table
-        table.set_sort_names({next(iterkeys(table.id_map)): 'Fake Sort'}, cache.backend)
+        table.set_sort_names({next(iter(table.id_map)): 'Fake Sort'}, cache.backend)
 
         authors = tuple(itervalues(table.id_map))
         nval = cache.author_sort_from_authors(authors)
diff --git a/src/calibre/db/view.py b/src/calibre/db/view.py
index 7fd51e783d..c183b9d65a 100644
--- a/src/calibre/db/view.py
+++ b/src/calibre/db/view.py
@@ -9,8 +9,8 @@ __docformat__ = 'restructuredtext en'
 
 import weakref, operator, numbers
 from functools import partial
-from polyglot.builtins import (iteritems, iterkeys, itervalues, map,
-        unicode_type, range, zip)
+from polyglot.builtins import (iteritems, itervalues, map,
+        unicode_type, range)
 
 from calibre.ebooks.metadata import title_sort
 from calibre.utils.config_base import tweaks, prefs
@@ -374,8 +374,7 @@ class View(object):
             self.marked_ids = dict.fromkeys(id_dict, u'true')
         else:
             # Ensure that all the items in the dict are text
-            self.marked_ids = dict(zip(iterkeys(id_dict), map(unicode_type,
-                itervalues(id_dict))))
+            self.marked_ids = {k: unicode_type(v) for k, v in iteritems(id_dict)}
         # This invalidates all searches in the cache even though the cache may
         # be shared by multiple views. This is not ideal, but...
         cmids = set(self.marked_ids)
diff --git a/src/calibre/devices/mtp/windows/driver.py b/src/calibre/devices/mtp/windows/driver.py
index f99a0309c6..7cfe575aea 100644
--- a/src/calibre/devices/mtp/windows/driver.py
+++ b/src/calibre/devices/mtp/windows/driver.py
@@ -9,7 +9,7 @@ __docformat__ = 'restructuredtext en'
 
 import time, threading, traceback
 from functools import wraps, partial
-from polyglot.builtins import iteritems, iterkeys, itervalues, unicode_type, zip
+from polyglot.builtins import iteritems, itervalues, unicode_type, zip
 from itertools import chain
 
 from calibre import as_unicode, prints, force_unicode
@@ -107,7 +107,7 @@ class MTP_DEVICE(MTPDeviceBase):
 
         # Get device data for detected devices. If there is an error, we will
         # try again for that device the next time this method is called.
-        for dev in tuple(iterkeys(self.detected_devices)):
+        for dev in tuple(self.detected_devices):
             data = self.detected_devices.get(dev, None)
             if data is None or data is False:
                 try:
diff --git a/src/calibre/devices/scanner.py b/src/calibre/devices/scanner.py
index 1eb5a24b95..3b8a141300 100644
--- a/src/calibre/devices/scanner.py
+++ b/src/calibre/devices/scanner.py
@@ -13,7 +13,7 @@ from threading import Lock
 from calibre import prints, as_unicode
 from calibre.constants import (iswindows, isosx, plugins, islinux, isfreebsd,
         isnetbsd)
-from polyglot.builtins import iterkeys, range
+from polyglot.builtins import range
 
 osx_scanner = linux_scanner = freebsd_scanner = netbsd_scanner = None
 
@@ -77,7 +77,7 @@ class LibUSBScanner(object):
             dev = USBDevice(*dev)
             dev.busnum, dev.devnum = fingerprint[:2]
             ans.add(dev)
-        extra = set(iterkeys(self.libusb.cache)) - seen
+        extra = set(self.libusb.cache) - seen
         for x in extra:
             self.libusb.cache.pop(x, None)
         return ans
diff --git a/src/calibre/devices/smart_device_app/driver.py b/src/calibre/devices/smart_device_app/driver.py
index 8dfe3f468e..560e25985a 100644
--- a/src/calibre/devices/smart_device_app/driver.py
+++ b/src/calibre/devices/smart_device_app/driver.py
@@ -1321,7 +1321,7 @@ class SMART_DEVICE_APP(DeviceConfig, DevicePlugin):
                 self._debug('processed cache. count=', len(books_on_device))
                 count_of_cache_items_deleted = 0
                 if self.client_cache_uses_lpaths:
-                    for lpath in tuple(self.known_metadata.iterkeys()):
+                    for lpath in tuple(self.known_metadata):
                         if lpath not in lpaths_on_device:
                             try:
                                 uuid = self.known_metadata[lpath].get('uuid', None)
diff --git a/src/calibre/ebooks/docx/cleanup.py b/src/calibre/ebooks/docx/cleanup.py
index 6d71805fc0..6a283a4b5c 100644
--- a/src/calibre/ebooks/docx/cleanup.py
+++ b/src/calibre/ebooks/docx/cleanup.py
@@ -7,7 +7,7 @@ __license__ = 'GPL v3'
 __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import os
-from polyglot.builtins import iterkeys, itervalues, range
+from polyglot.builtins import itervalues, range
 
 NBSP = '\xa0'
 
@@ -54,7 +54,7 @@ def merge_run(run):
 def liftable(css):
     # A <span> is liftable if all its styling would work just as well if it is
     # specified on the parent element.
-    prefixes = {x.partition('-')[0] for x in iterkeys(css)}
+    prefixes = {x.partition('-')[0] for x in css}
     return not (prefixes - {'text', 'font', 'letter', 'color', 'background'})
 
 
diff --git a/src/calibre/ebooks/docx/writer/styles.py b/src/calibre/ebooks/docx/writer/styles.py
index f1c918ad6b..272553f33d 100644
--- a/src/calibre/ebooks/docx/writer/styles.py
+++ b/src/calibre/ebooks/docx/writer/styles.py
@@ -15,7 +15,7 @@ from lxml import etree
 from calibre.ebooks import parse_css_length
 from calibre.ebooks.docx.writer.utils import convert_color, int_or_zero
 from calibre.utils.localization import lang_as_iso639_1
-from polyglot.builtins import iteritems, iterkeys, unicode_type
+from polyglot.builtins import iteritems, unicode_type
 from tinycss.css21 import CSS21Parser
 
 css_parser = CSS21Parser()
@@ -721,7 +721,7 @@ class StylesManager(object):
                     heading_styles.append(style)
                 style.id = style.name = val
             style.seq = i
-        self.combined_styles = sorted(iterkeys(counts), key=attrgetter('seq'))
+        self.combined_styles = sorted(counts, key=attrgetter('seq'))
         [ls.apply() for ls in self.combined_styles]
 
         descendant_style_map = {}
diff --git a/src/calibre/ebooks/metadata/book/base.py b/src/calibre/ebooks/metadata/book/base.py
index 4bb37b6c9b..97e84827c6 100644
--- a/src/calibre/ebooks/metadata/book/base.py
+++ b/src/calibre/ebooks/metadata/book/base.py
@@ -14,7 +14,7 @@ from calibre.ebooks.metadata.book import (SC_COPYABLE_FIELDS,
         TOP_LEVEL_IDENTIFIERS, ALL_METADATA_FIELDS)
 from calibre.library.field_metadata import FieldMetadata
 from calibre.utils.icu import sort_key
-from polyglot.builtins import iteritems, iterkeys, unicode_type
+from polyglot.builtins import iteritems, unicode_type
 
 # Special sets used to optimize the performance of getting and setting
 # attributes on Metadata objects
@@ -137,7 +137,7 @@ class Metadata(object):
             return object.__getattribute__(self, field)
         except AttributeError:
             pass
-        if field in iterkeys(_data['user_metadata']):
+        if field in _data['user_metadata']:
             d = _data['user_metadata'][field]
             val = d['#value#']
             if d['datatype'] != 'composite':
@@ -180,7 +180,7 @@ class Metadata(object):
             if val and val.lower() != 'und':
                 langs = [val]
             _data['languages'] = langs
-        elif field in iterkeys(_data['user_metadata']):
+        elif field in _data['user_metadata']:
             _data['user_metadata'][field]['#value#'] = val
             _data['user_metadata'][field]['#extra#'] = extra
         else:
@@ -190,7 +190,7 @@ class Metadata(object):
             self.__dict__[field] = val
 
     def __iter__(self):
-        return iterkeys(object.__getattribute__(self, '_data'))
+        return iter(object.__getattribute__(self, '_data'))
 
     def has_key(self, key):
         return key in object.__getattribute__(self, '_data')
@@ -219,7 +219,7 @@ class Metadata(object):
 
     def get_extra(self, field, default=None):
         _data = object.__getattribute__(self, '_data')
-        if field in iterkeys(_data['user_metadata']):
+        if field in _data['user_metadata']:
             try:
                 return _data['user_metadata'][field]['#extra#']
             except:
@@ -287,14 +287,14 @@ class Metadata(object):
         '''
         return a list of the custom fields in this book
         '''
-        return iterkeys(object.__getattribute__(self, '_data')['user_metadata'])
+        return iter(object.__getattribute__(self, '_data')['user_metadata'])
 
     def all_field_keys(self):
         '''
         All field keys known by this instance, even if their value is None
         '''
         _data = object.__getattribute__(self, '_data')
-        return frozenset(ALL_METADATA_FIELDS.union(iterkeys(_data['user_metadata'])))
+        return frozenset(ALL_METADATA_FIELDS.union(frozenset(_data['user_metadata'])))
 
     def metadata_for_field(self, key):
         '''
@@ -320,7 +320,7 @@ class Metadata(object):
             v = self.get(attr, None)
             if v is not None:
                 result[attr] = v
-        for attr in iterkeys(_data['user_metadata']):
+        for attr in _data['user_metadata']:
             v = self.get(attr, None)
             if v is not None:
                 result[attr] = v
diff --git a/src/calibre/ebooks/metadata/sources/google_images.py b/src/calibre/ebooks/metadata/sources/google_images.py
index a40eca4589..39cd9d2197 100644
--- a/src/calibre/ebooks/metadata/sources/google_images.py
+++ b/src/calibre/ebooks/metadata/sources/google_images.py
@@ -91,7 +91,7 @@ class GoogleImages(Source):
                 continue
             if 'ou' in data:
                 ans[data['ou']] = True
-        return list(ans.iterkeys())
+        return list(ans)
 
 
 def test():
diff --git a/src/calibre/ebooks/metadata/sources/identify.py b/src/calibre/ebooks/metadata/sources/identify.py
index c807d0e87a..ca3f5b606e 100644
--- a/src/calibre/ebooks/metadata/sources/identify.py
+++ b/src/calibre/ebooks/metadata/sources/identify.py
@@ -27,7 +27,7 @@ from calibre.utils.html2text import html2text
 from calibre.utils.icu import lower
 from calibre.utils.date import UNDEFINED_DATE
 from calibre.utils.formatter import EvalFormatter
-from polyglot.builtins import iteritems, iterkeys, itervalues, unicode_type
+from polyglot.builtins import iteritems, itervalues, unicode_type
 
 # Download worker {{{
 
@@ -439,7 +439,7 @@ def identify(log, abort,  # {{{
         pass
 
     sort_kwargs = dict(kwargs)
-    for k in list(iterkeys(sort_kwargs)):
+    for k in list(sort_kwargs):
         if k not in ('title', 'authors', 'identifiers'):
             sort_kwargs.pop(k)
 
diff --git a/src/calibre/ebooks/mobi/debug/index.py b/src/calibre/ebooks/mobi/debug/index.py
index e9446f266f..0f84e99575 100644
--- a/src/calibre/ebooks/mobi/debug/index.py
+++ b/src/calibre/ebooks/mobi/debug/index.py
@@ -15,7 +15,7 @@ from calibre.ebooks.mobi.reader.headers import NULL_INDEX
 from calibre.ebooks.mobi.reader.index import (CNCX, parse_indx_header,
         parse_tagx_section, parse_index_record, INDEX_HEADER_FIELDS)
 from calibre.ebooks.mobi.reader.ncx import (tag_fieldname_map, default_entry)
-from polyglot.builtins import iteritems, iterkeys, range
+from polyglot.builtins import iteritems, range
 
 File = namedtuple('File',
     'file_number name divtbl_count start_position length')
@@ -140,11 +140,11 @@ class SKELIndex(Index):
         self.records = []
 
         if self.table is not None:
-            for i, text in enumerate(iterkeys(self.table)):
+            for i, text in enumerate(self.table):
                 tag_map = self.table[text]
-                if set(iterkeys(tag_map)) != {1, 6}:
+                if set(tag_map) != {1, 6}:
                     raise ValueError('SKEL Index has unknown tags: %s'%
-                            (set(iterkeys(tag_map))-{1,6}))
+                            (set(tag_map)-{1,6}))
                 self.records.append(File(
                     i,  # file_number
                     text,  # name
@@ -161,11 +161,11 @@ class SECTIndex(Index):
         self.records = []
 
         if self.table is not None:
-            for i, text in enumerate(iterkeys(self.table)):
+            for i, text in enumerate(self.table):
                 tag_map = self.table[text]
-                if set(iterkeys(tag_map)) != {2, 3, 4, 6}:
+                if set(tag_map) != {2, 3, 4, 6}:
                     raise ValueError('Chunk Index has unknown tags: %s'%
-                            (set(iterkeys(tag_map))-{2, 3, 4, 6}))
+                            (set(tag_map)-{2, 3, 4, 6}))
 
                 toc_text = self.cncx[tag_map[2][0]]
                 self.records.append(Elem(
@@ -186,9 +186,9 @@ class GuideIndex(Index):
         self.records = []
 
         if self.table is not None:
-            for i, text in enumerate(iterkeys(self.table)):
+            for i, text in enumerate(self.table):
                 tag_map = self.table[text]
-                if set(iterkeys(tag_map)) not in ({1, 6}, {1, 2, 3}):
+                if set(tag_map) not in ({1, 6}, {1, 2, 3}):
                     raise ValueError('Guide Index has unknown tags: %s'%
                             tag_map)
 
@@ -217,7 +217,7 @@ class NCXIndex(Index):
                 entry['name'] = text
                 entry['num'] = num
 
-                for tag in iterkeys(tag_fieldname_map):
+                for tag in tag_fieldname_map:
                     fieldname, i = tag_fieldname_map[tag]
                     if tag in tag_map:
                         fieldvalue = tag_map[tag][i]
diff --git a/src/calibre/ebooks/mobi/reader/mobi8.py b/src/calibre/ebooks/mobi/reader/mobi8.py
index a1a0cfecc1..07d72f1d36 100644
--- a/src/calibre/ebooks/mobi/reader/mobi8.py
+++ b/src/calibre/ebooks/mobi/reader/mobi8.py
@@ -24,7 +24,7 @@ from calibre.ebooks.metadata.toc import TOC
 from calibre.ebooks.mobi.utils import read_font_record
 from calibre.ebooks.oeb.parse_utils import parse_html
 from calibre.ebooks.oeb.base import XPath, XHTML, xml2text
-from polyglot.builtins import iterkeys, range, zip
+from polyglot.builtins import range, zip
 from polyglot.urllib import urldefrag
 
 Part = namedtuple('Part',
@@ -134,7 +134,7 @@ class Mobi8Reader(object):
             File = namedtuple('File',
                 'file_number name divtbl_count start_position length')
 
-            for i, text in enumerate(iterkeys(table)):
+            for i, text in enumerate(table):
                 tag_map = table[text]
                 self.files.append(File(i, text, tag_map[1][0],
                     tag_map[6][0], tag_map[6][1]))
@@ -143,7 +143,7 @@ class Mobi8Reader(object):
         if self.header.dividx != NULL_INDEX:
             table, cncx = read_index(self.kf8_sections, self.header.dividx,
                     self.header.codec)
-            for i, text in enumerate(iterkeys(table)):
+            for i, text in enumerate(table):
                 tag_map = table[text]
                 toc_text = cncx[tag_map[2][0]]
                 self.elems.append(Elem(int(text), toc_text, tag_map[3][0],
@@ -156,7 +156,7 @@ class Mobi8Reader(object):
             Item = namedtuple('Item',
                 'type title pos_fid')
 
-            for i, ref_type in enumerate(iterkeys(table)):
+            for i, ref_type in enumerate(table):
                 tag_map = table[ref_type]
                 # ref_type, ref_title, div/frag number
                 title = cncx[tag_map[1][0]]
diff --git a/src/calibre/ebooks/mobi/reader/ncx.py b/src/calibre/ebooks/mobi/reader/ncx.py
index cc87ea1b07..c98b6aa891 100644
--- a/src/calibre/ebooks/mobi/reader/ncx.py
+++ b/src/calibre/ebooks/mobi/reader/ncx.py
@@ -13,7 +13,7 @@ from calibre import replace_entities
 from calibre.ebooks.metadata.toc import TOC
 from calibre.ebooks.mobi.reader.headers import NULL_INDEX
 from calibre.ebooks.mobi.reader.index import read_index
-from polyglot.builtins import iteritems, iterkeys
+from polyglot.builtins import iteritems
 
 tag_fieldname_map = {
         1:  ['pos',0],
@@ -63,7 +63,7 @@ def read_ncx(sections, index, codec):
             entry['name'] = text
             entry['num'] = num
 
-            for tag in iterkeys(tag_fieldname_map):
+            for tag in tag_fieldname_map:
                 fieldname, i = tag_fieldname_map[tag]
                 if tag in tag_map:
                     fieldvalue = tag_map[tag][i]
diff --git a/src/calibre/ebooks/mobi/utils.py b/src/calibre/ebooks/mobi/utils.py
index 6760605650..4ca8eec878 100644
--- a/src/calibre/ebooks/mobi/utils.py
+++ b/src/calibre/ebooks/mobi/utils.py
@@ -14,7 +14,7 @@ from io import BytesIO
 from calibre.utils.img import save_cover_data_to, scale_image, image_to_data, image_from_data, resize_image
 from calibre.utils.imghdr import what
 from calibre.ebooks import normalize
-from polyglot.builtins import iterkeys, unicode_type, range
+from polyglot.builtins import unicode_type, range
 from tinycss.color3 import parse_color_string
 
 IMAGE_MAX_SIZE = 10 * 1024 * 1024
@@ -589,7 +589,7 @@ class CNCX(object):  # {{{
         offset = 0
         buf = BytesIO()
         RECORD_LIMIT = 0x10000 - 1024  # kindlegen appears to use 1024, PDB limit is 0x10000
-        for key in iterkeys(self.strings):
+        for key in self.strings:
             utf8 = utf8_text(key[:self.MAX_STRING_LENGTH])
             l = len(utf8)
             sz_bytes = encint(l)
diff --git a/src/calibre/ebooks/mobi/writer2/indexer.py b/src/calibre/ebooks/mobi/writer2/indexer.py
index 68ec0633c7..2d415fcea4 100644
--- a/src/calibre/ebooks/mobi/writer2/indexer.py
+++ b/src/calibre/ebooks/mobi/writer2/indexer.py
@@ -14,7 +14,7 @@ from collections import OrderedDict, defaultdict
 
 from calibre.ebooks.mobi.utils import (encint, encode_number_as_hex,
         encode_tbs, align_block, RECORD_SIZE, CNCX as CNCX_)
-from polyglot.builtins import filter, iteritems, iterkeys, itervalues, map, range
+from polyglot.builtins import filter, iteritems, itervalues, map, range
 
 
 class CNCX(CNCX_):  # {{{
@@ -317,7 +317,7 @@ class TBS(object):  # {{{
             if first_node is not None and first_node.depth > 0:
                 parent_section_index = (first_node.index if first_node.depth == 1 else first_node.parent_index)
             else:
-                parent_section_index = max(iterkeys(self.section_map))
+                parent_section_index = max(iter(self.section_map))
 
         else:
             # Non terminal record
diff --git a/src/calibre/ebooks/oeb/polish/main.py b/src/calibre/ebooks/oeb/polish/main.py
index 655b80b24c..11cc0519ca 100644
--- a/src/calibre/ebooks/oeb/polish/main.py
+++ b/src/calibre/ebooks/oeb/polish/main.py
@@ -23,7 +23,7 @@ from calibre.ebooks.oeb.polish.jacket import (
     replace_jacket, add_or_replace_jacket, find_existing_jacket, remove_jacket)
 from calibre.ebooks.oeb.polish.css import remove_unused_css
 from calibre.utils.logging import Log
-from polyglot.builtins import iteritems, iterkeys
+from polyglot.builtins import iteritems
 
 ALL_OPTS = {
     'embed': False,
@@ -264,7 +264,7 @@ def gui_polish(data):
     file_map = {x:x for x in files}
     opts = ALL_OPTS.copy()
     opts.update(data)
-    O = namedtuple('Options', ' '.join(iterkeys(ALL_OPTS)))
+    O = namedtuple('Options', ' '.join(ALL_OPTS))
     opts = O(**opts)
     log = Log(level=Log.DEBUG)
     report = []
@@ -279,7 +279,7 @@ def gui_polish(data):
 def tweak_polish(container, actions, customization=None):
     opts = ALL_OPTS.copy()
     opts.update(actions)
-    O = namedtuple('Options', ' '.join(iterkeys(ALL_OPTS)))
+    O = namedtuple('Options', ' '.join(ALL_OPTS))
     opts = O(**opts)
     report = []
     changed = polish_one(container, opts, report.append, customization=customization)
@@ -335,7 +335,7 @@ def main(args=None):
     for k, v in iteritems(popts):
         popts[k] = getattr(opts, k, None)
 
-    O = namedtuple('Options', ' '.join(iterkeys(popts)))
+    O = namedtuple('Options', ' '.join(popts))
     popts = O(**popts)
     report = []
     if not tuple(filter(None, (getattr(popts, name) for name in ALL_OPTS))):
diff --git a/src/calibre/ebooks/oeb/transforms/flatcss.py b/src/calibre/ebooks/oeb/transforms/flatcss.py
index a4efb4c9ac..cacc4684ca 100644
--- a/src/calibre/ebooks/oeb/transforms/flatcss.py
+++ b/src/calibre/ebooks/oeb/transforms/flatcss.py
@@ -21,7 +21,7 @@ from calibre.ebooks.oeb.base import (XHTML, XHTML_NS, CSS_MIME, OEB_STYLES,
 from calibre.ebooks.oeb.stylizer import Stylizer
 from calibre.utils.filenames import ascii_filename, ascii_text
 from calibre.utils.icu import numeric_sort_key
-from polyglot.builtins import iteritems, iterkeys, unicode_type, string_or_bytes
+from polyglot.builtins import iteritems, unicode_type, string_or_bytes
 
 COLLAPSE = re.compile(r'[ \t\r\n\v]+')
 STRIPNUM = re.compile(r'[-0-9]+$')
@@ -674,7 +674,7 @@ class CSSFlattener(object):
             self.flatten_node(body, stylizer, names, styles, pseudo_styles, fsize, item.id)
         items = sorted(((key, val) for (val, key) in iteritems(styles)), key=lambda x:numeric_sort_key(x[0]))
         # :hover must come after link and :active must come after :hover
-        psels = sorted(iterkeys(pseudo_styles), key=lambda x :
+        psels = sorted(pseudo_styles, key=lambda x :
                 {'hover':1, 'active':2}.get(x, 0))
         for psel in psels:
             styles = pseudo_styles[psel]
diff --git a/src/calibre/ebooks/pdf/render/common.py b/src/calibre/ebooks/pdf/render/common.py
index 8c89f2589c..eb53bb9031 100644
--- a/src/calibre/ebooks/pdf/render/common.py
+++ b/src/calibre/ebooks/pdf/render/common.py
@@ -14,7 +14,7 @@ from binascii import hexlify
 
 from calibre.constants import plugins, ispy3
 from calibre.utils.logging import default_log
-from polyglot.builtins import iteritems, iterkeys, unicode_type
+from polyglot.builtins import iteritems, unicode_type
 
 pdf_float = plugins['speedup'][0].pdf_float
 
@@ -146,7 +146,7 @@ class Dictionary(dict):
 
     def pdf_serialize(self, stream):
         stream.write(b'<<' + EOL)
-        sorted_keys = sorted(iterkeys(self),
+        sorted_keys = sorted(self,
                              key=lambda x:({'Type':'1', 'Subtype':'2'}.get(
                                  x, x)+x))
         for k in sorted_keys:
diff --git a/src/calibre/ebooks/pdf/render/fonts.py b/src/calibre/ebooks/pdf/render/fonts.py
index aca2292c77..1853ba5eb2 100644
--- a/src/calibre/ebooks/pdf/render/fonts.py
+++ b/src/calibre/ebooks/pdf/render/fonts.py
@@ -11,7 +11,7 @@ import re
 from itertools import groupby
 from operator import itemgetter
 from collections import Counter, OrderedDict
-from polyglot.builtins import iteritems, iterkeys, map, zip
+from polyglot.builtins import iteritems, map, zip
 
 from calibre import as_unicode
 from calibre.ebooks.pdf.render.common import (Array, String, Stream,
@@ -204,7 +204,7 @@ class Font(object):
         widths = {g:w for g, w in iteritems(widths) if w != most_common}
 
         groups = Array()
-        for k, g in groupby(enumerate(iterkeys(widths)), lambda i_x:i_x[0]-i_x[1]):
+        for k, g in groupby(enumerate(widths), lambda i_x:i_x[0]-i_x[1]):
             group = list(map(itemgetter(1), g))
             gwidths = [widths[g] for g in group]
             if len(set(gwidths)) == 1 and len(group) > 1:
diff --git a/src/calibre/gui2/actions/choose_library.py b/src/calibre/gui2/actions/choose_library.py
index 19ccb10311..a8adb593e4 100644
--- a/src/calibre/gui2/actions/choose_library.py
+++ b/src/calibre/gui2/actions/choose_library.py
@@ -20,7 +20,7 @@ from calibre.utils.icu import sort_key
 from calibre.gui2 import (gprefs, warning_dialog, Dispatcher, error_dialog,
     question_dialog, info_dialog, open_local_file, choose_dir)
 from calibre.gui2.actions import InterfaceAction
-from polyglot.builtins import iterkeys, unicode_type, range
+from polyglot.builtins import unicode_type, range
 
 
 def db_class():
@@ -40,7 +40,7 @@ class LibraryUsageStats(object):  # {{{
                 # Rename the current library. Renaming of other libraries is
                 # handled by the switch function
                 q = os.path.basename(lp)
-                for loc in list(iterkeys(self.stats)):
+                for loc in list(self.stats):
                     bn = posixpath.basename(loc)
                     if bn.lower() == q.lower():
                         self.rename(loc, lp)
diff --git a/src/calibre/gui2/dialogs/opml.py b/src/calibre/gui2/dialogs/opml.py
index 2b6bde5f3f..209198c808 100644
--- a/src/calibre/gui2/dialogs/opml.py
+++ b/src/calibre/gui2/dialogs/opml.py
@@ -17,7 +17,7 @@ from lxml import etree
 
 from calibre.gui2 import choose_files, error_dialog
 from calibre.utils.icu import sort_key
-from polyglot.builtins import iterkeys, unicode_type
+from polyglot.builtins import unicode_type
 
 Group = namedtuple('Group', 'title feeds')
 
@@ -49,7 +49,7 @@ def import_opml(raw, preserve_groups=True):
                         break
         groups[parent].append((title, url))
 
-    for title in sorted(iterkeys(groups), key=sort_key):
+    for title in sorted(groups, key=sort_key):
         yield Group(title, uniq(groups[title], kmap=itemgetter(1)))
 
 
diff --git a/src/calibre/gui2/icon_theme.py b/src/calibre/gui2/icon_theme.py
index d8d6b839bc..e4c48f9562 100644
--- a/src/calibre/gui2/icon_theme.py
+++ b/src/calibre/gui2/icon_theme.py
@@ -36,7 +36,7 @@ from calibre.utils.zipfile import ZipFile, ZIP_STORED
 from calibre.utils.filenames import atomic_rename
 from lzma.xz import compress, decompress
 from polyglot.queue import Queue, Empty
-from polyglot.builtins import iteritems, iterkeys, map, range, reraise
+from polyglot.builtins import iteritems, map, range, reraise
 
 IMAGE_EXTENSIONS = {'png', 'jpg', 'jpeg'}
 THEME_COVER = 'icon-theme-cover.jpg'
@@ -362,7 +362,7 @@ def create_themeball(report, progress=None, abort=None):
         except Exception:
             return sys.exc_info()
 
-    errors = tuple(filter(None, pool.map(optimize, tuple(iterkeys(report.name_map)))))
+    errors = tuple(filter(None, pool.map(optimize, tuple(report.name_map))))
     pool.close(), pool.join()
     if abort is not None and abort.is_set():
         return
diff --git a/src/calibre/gui2/library/caches.py b/src/calibre/gui2/library/caches.py
index dd0b925003..d622507ab7 100644
--- a/src/calibre/gui2/library/caches.py
+++ b/src/calibre/gui2/library/caches.py
@@ -12,7 +12,7 @@ from collections import OrderedDict
 from PyQt5.Qt import QImage, QPixmap
 
 from calibre.db.utils import ThumbnailCache as TC
-from polyglot.builtins import interkeys, itervalues
+from polyglot.builtins import itervalues
 
 
 class ThumbnailCache(TC):
@@ -68,7 +68,7 @@ class CoverCache(dict):
             self._pop(key)  # pop() so that item is moved to the top
             self.items[key] = val
             if len(self.items) > self.limit:
-                del self.items[next(iterkeys(self.items))]
+                del self.items[next(iter(self.items))]
 
     def clear(self):
         with self.lock:
@@ -85,6 +85,6 @@ class CoverCache(dict):
             self.limit = limit
             if len(self.items) > self.limit:
                 extra = len(self.items) - self.limit
-                remove = tuple(iterkeys(self))[:extra]
+                remove = tuple(self)[:extra]
                 for k in remove:
                     self._pop(k)
diff --git a/src/calibre/gui2/preferences/behavior.py b/src/calibre/gui2/preferences/behavior.py
index 5acc1ffd2b..badbbbff24 100644
--- a/src/calibre/gui2/preferences/behavior.py
+++ b/src/calibre/gui2/preferences/behavior.py
@@ -18,7 +18,7 @@ from calibre.ebooks import BOOK_EXTENSIONS
 from calibre.ebooks.oeb.iterator import is_supported
 from calibre.constants import iswindows
 from calibre.utils.icu import sort_key
-from polyglot.builtins import iterkeys, unicode_type
+from polyglot.builtins import unicode_type
 
 
 class OutputFormatSetting(Setting):
@@ -50,7 +50,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         choices = [(x.upper(), x) for x in output_formats]
         r('output_format', prefs, choices=choices, setting=OutputFormatSetting)
 
-        restrictions = sorted(iterkeys(db.prefs['virtual_libraries']), key=sort_key)
+        restrictions = sorted(db.prefs['virtual_libraries'], key=sort_key)
         choices = [('', '')] + [(x, x) for x in restrictions]
         # check that the virtual library still exists
         vls = db.prefs['virtual_lib_on_startup']
diff --git a/src/calibre/gui2/preferences/tweaks.py b/src/calibre/gui2/preferences/tweaks.py
index bec93d7226..d87e1c65c3 100644
--- a/src/calibre/gui2/preferences/tweaks.py
+++ b/src/calibre/gui2/preferences/tweaks.py
@@ -19,7 +19,7 @@ from calibre import isbytestring
 from calibre.utils.icu import lower
 from calibre.utils.search_query_parser import (ParseException,
         SearchQueryParser)
-from polyglot.builtins import iteritems, iterkeys, unicode_type, range
+from polyglot.builtins import iteritems, unicode_type, range
 
 from PyQt5.Qt import (
     QAbstractListModel, Qt, QStyledItemDelegate, QStyle, QStyleOptionViewItem,
@@ -188,8 +188,8 @@ class Tweaks(QAbstractListModel, AdaptSQP):  # {{{
             pos += 1
 
         self.tweaks.sort()
-        default_keys = set(iterkeys(dl))
-        custom_keys = set(iterkeys(l))
+        default_keys = set(dl)
+        custom_keys = set(l)
 
         self.plugin_tweaks = {}
         for key in custom_keys - default_keys:
diff --git a/src/calibre/gui2/tweak_book/editor/themes.py b/src/calibre/gui2/tweak_book/editor/themes.py
index 758c931d6f..46e1163814 100644
--- a/src/calibre/gui2/tweak_book/editor/themes.py
+++ b/src/calibre/gui2/tweak_book/editor/themes.py
@@ -18,7 +18,7 @@ from calibre.gui2 import error_dialog
 from calibre.gui2.tweak_book import tprefs
 from calibre.gui2.tweak_book.editor import syntax_text_char_format
 from calibre.gui2.tweak_book.widgets import Dialog
-from polyglot.builtins import iteritems, iterkeys, unicode_type, range
+from polyglot.builtins import iteritems, unicode_type, range
 
 underline_styles = {'single', 'dash', 'dot', 'dash_dot', 'dash_dot_dot', 'wave', 'spell'}
 
@@ -310,11 +310,11 @@ def theme_format(theme, name):
 
 
 def custom_theme_names():
-    return tuple(iterkeys(tprefs['custom_themes']))
+    return tuple(tprefs['custom_themes'])
 
 
 def builtin_theme_names():
-    return tuple(iterkeys(THEMES))
+    return tuple(THEMES)
 
 
 def all_theme_names():
@@ -612,8 +612,8 @@ class ThemeEditor(Dialog):
 
     def update_theme(self, name):
         data = tprefs['custom_themes'][name]
-        extra = set(iterkeys(data)) - set(iterkeys(THEMES[default_theme()]))
-        missing = set(iterkeys(THEMES[default_theme()])) - set(iterkeys(data))
+        extra = set(data) - set(THEMES[default_theme()])
+        missing = set(THEMES[default_theme()]) - set(data)
         for k in extra:
             data.pop(k)
         for k in missing:
diff --git a/src/calibre/gui2/tweak_book/manage_fonts.py b/src/calibre/gui2/tweak_book/manage_fonts.py
index bc1d0c06f3..58b51eb58c 100644
--- a/src/calibre/gui2/tweak_book/manage_fonts.py
+++ b/src/calibre/gui2/tweak_book/manage_fonts.py
@@ -22,7 +22,7 @@ from calibre.gui2.tweak_book.widgets import Dialog, BusyCursor
 from calibre.utils.icu import primary_sort_key as sort_key
 from calibre.utils.fonts.scanner import font_scanner, NoFonts
 from calibre.utils.fonts.metadata import FontMetadata, UnsupportedFont
-from polyglot.builtins import iteritems, iterkeys, unicode_type
+from polyglot.builtins import iteritems, unicode_type
 
 
 def show_font_face_rule_for_font_file(file_data, added_name, parent=None):
@@ -103,7 +103,7 @@ class AllFonts(QAbstractTableModel):
 
     def do_sort(self):
         reverse = not self.sorted_on[1]
-        self.items = sorted(iterkeys(self.font_data), key=sort_key, reverse=reverse)
+        self.items = sorted(self.font_data, key=sort_key, reverse=reverse)
         if self.sorted_on[0] != 'name':
             self.items.sort(key=self.font_data.get, reverse=reverse)
 
diff --git a/src/calibre/gui2/tweak_book/preferences.py b/src/calibre/gui2/tweak_book/preferences.py
index 5ee795480e..470e476285 100644
--- a/src/calibre/gui2/tweak_book/preferences.py
+++ b/src/calibre/gui2/tweak_book/preferences.py
@@ -10,7 +10,7 @@ import numbers
 from operator import attrgetter, methodcaller
 from collections import namedtuple
 from polyglot.builtins import (
-        iteritems, iterkeys, itervalues, map, unicode_type, range)
+        iteritems, itervalues, map, unicode_type, range)
 from itertools import product
 from copy import copy, deepcopy
 
@@ -594,7 +594,7 @@ class TemplatesDialog(Dialog):  # {{{
         self.l = l = QVBoxLayout(self)
 
         self.syntaxes = s = QComboBox(self)
-        s.addItems(sorted(iterkeys(DEFAULT_TEMPLATES)))
+        s.addItems(sorted(DEFAULT_TEMPLATES))
         s.setCurrentIndex(s.findText('html'))
         h = QHBoxLayout()
         l.addLayout(h)
diff --git a/src/calibre/gui2/tweak_book/search.py b/src/calibre/gui2/tweak_book/search.py
index abe2535916..de8397b5ca 100644
--- a/src/calibre/gui2/tweak_book/search.py
+++ b/src/calibre/gui2/tweak_book/search.py
@@ -34,7 +34,7 @@ from calibre.gui2.tweak_book.widgets import BusyCursor
 from calibre.gui2.widgets2 import FlowLayout, HistoryComboBox
 from calibre.utils.icu import primary_contains
 from calibre.ebooks.conversion.search_replace import REGEX_FLAGS, compile_regular_expression
-from polyglot.builtins import iteritems, iterkeys, unicode_type, range
+from polyglot.builtins import iteritems, unicode_type, range
 
 
 # The search panel {{{
@@ -1220,7 +1220,7 @@ class SavedSearches(QWidget):
                 return err()
             searches = []
             for item in obj['searches']:
-                if not isinstance(item, dict) or not set(iterkeys(item)).issuperset(needed_keys):
+                if not isinstance(item, dict) or not set(item).issuperset(needed_keys):
                     return err
                 searches.append({k:item[k] for k in needed_keys})
 
diff --git a/src/calibre/gui2/viewer/config.py b/src/calibre/gui2/viewer/config.py
index 2eae758e1d..8f310d53e8 100644
--- a/src/calibre/gui2/viewer/config.py
+++ b/src/calibre/gui2/viewer/config.py
@@ -22,7 +22,7 @@ from calibre.gui2 import min_available_height, error_dialog
 from calibre.gui2.languages import LanguagesEdit
 from calibre.gui2.shortcuts import ShortcutConfig
 from calibre.gui2.viewer.config_ui import Ui_Dialog
-from polyglot.builtins import iteritems, iterkeys, unicode_type
+from polyglot.builtins import iteritems, unicode_type
 
 
 def config(defaults=None):
@@ -213,7 +213,7 @@ class ConfigDialog(QDialog, Ui_Dialog):
         for x in ('load', 'delete'):
             m = getattr(self, '%s_theme_button'%x).menu()
             m.clear()
-            for x in iterkeys(self.themes):
+            for x in self.themes:
                 title = x[len('theme_'):]
                 ac = m.addAction(title)
                 ac.theme_id = x
diff --git a/src/calibre/library/caches.py b/src/calibre/library/caches.py
index c8fdfbf5c9..21413d4e31 100644
--- a/src/calibre/library/caches.py
+++ b/src/calibre/library/caches.py
@@ -20,7 +20,7 @@ from calibre.db.search import CONTAINS_MATCH, EQUALS_MATCH, REGEXP_MATCH, _match
 from calibre.ebooks.metadata import title_sort, author_to_author_sort
 from calibre.ebooks.metadata.opf2 import metadata_to_opf
 from calibre import prints, force_unicode
-from polyglot.builtins import (iteritems, iterkeys, itervalues, map,
+from polyglot.builtins import (iteritems, itervalues, map,
         unicode_type, string_or_bytes, zip)
 
 
@@ -918,7 +918,7 @@ class ResultCache(SearchQueryParser):  # {{{
             self.marked_ids_dict = dict.fromkeys(id_dict, u'true')
         else:
             # Ensure that all the items in the dict are text
-            self.marked_ids_dict = dict(zip(iterkeys(id_dict), map(unicode_type,
+            self.marked_ids_dict = dict(zip(iter(id_dict), map(unicode_type,
                 itervalues(id_dict))))
 
         # Set the values in the cache
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index 80f11ea65e..02c76a9f97 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -47,7 +47,7 @@ from calibre.db.lazy import FormatMetadata, FormatsList
 from calibre.db.categories import Tag, CATEGORY_SORTS
 from calibre.utils.localization import (canonicalize_lang,
         calibre_langcode_to_name)
-from polyglot.builtins import iteritems, iterkeys, unicode_type, string_or_bytes
+from polyglot.builtins import iteritems, unicode_type, string_or_bytes
 
 copyfile = os.link if hasattr(os, 'link') else shutil.copyfile
 SPOOL_SIZE = 30*1024*1024
@@ -1798,7 +1798,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
 
         # First, build the maps. We need a category->items map and an
         # item -> (item_id, sort_val) map to use in the books loop
-        for category in iterkeys(tb_cats):
+        for category in tb_cats:
             cat = tb_cats[category]
             if not cat['is_category'] or cat['kind'] in ['user', 'search'] \
                     or category in ['news', 'formats'] or cat.get('is_csp',
@@ -1854,7 +1854,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             md.append((category, cat['rec_index'],
                        cat['is_multiple'].get('cache_to_list', None), False))
 
-        for category in iterkeys(tb_cats):
+        for category in tb_cats:
             cat = tb_cats[category]
             if cat['datatype'] == 'composite' and \
                                 cat['display'].get('make_category', False):
@@ -1959,7 +1959,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         # and building the Tag instances.
         categories = {}
         tag_class = Tag
-        for category in iterkeys(tb_cats):
+        for category in tb_cats:
             if category not in tcategories:
                 continue
             cat = tb_cats[category]
@@ -2373,7 +2373,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             self.set_identifiers(id, identifiers, notify=False, commit=False)
 
         user_mi = mi.get_all_user_metadata(make_copy=False)
-        for key in iterkeys(user_mi):
+        for key in user_mi:
             if key in self.field_metadata and \
                     user_mi[key]['datatype'] == self.field_metadata[key]['datatype'] and \
                     (user_mi[key]['datatype'] != 'text' or
diff --git a/src/calibre/library/field_metadata.py b/src/calibre/library/field_metadata.py
index 9abdd6d853..523f322521 100644
--- a/src/calibre/library/field_metadata.py
+++ b/src/calibre/library/field_metadata.py
@@ -7,7 +7,7 @@ import traceback
 from collections import OrderedDict
 
 from calibre.utils.config_base import tweaks
-from polyglot.builtins import iteritems, iterkeys, itervalues
+from polyglot.builtins import iteritems, itervalues
 
 category_icon_map = {
                     'authors'    : 'user_profile.png',
@@ -509,7 +509,7 @@ class FieldMetadata(object):
         return self.is_custom_field(key) or key.startswith('@')
 
     def ignorable_field_keys(self):
-        return [k for k in iterkeys(self._tb_cats) if self.is_ignorable_field(k)]
+        return [k for k in self._tb_cats if self.is_ignorable_field(k)]
 
     def is_series_index(self, key):
         try:
diff --git a/src/calibre/library/restore.py b/src/calibre/library/restore.py
index 4a2f428f60..153d005dd1 100644
--- a/src/calibre/library/restore.py
+++ b/src/calibre/library/restore.py
@@ -16,8 +16,7 @@ from calibre.library.prefs import DBPrefs
 from calibre.constants import filesystem_encoding
 from calibre.utils.date import utcfromtimestamp
 from calibre import isbytestring
-from polyglot.builtins import iteritems, iterkeys
-i
+from polyglot.builtins import iteritems
 
 NON_EBOOK_EXTENSIONS = frozenset([
         'jpg', 'jpeg', 'gif', 'png', 'bmp',
@@ -249,7 +248,7 @@ class Restore(Thread):
                 self.failed_restores.append((book, traceback.format_exc()))
             self.progress_callback(book['mi'].title, i+1)
 
-        for author in iterkeys(self.authors_links):
+        for author in self.authors_links:
             link, ign = self.authors_links[author]
             db.conn.execute('UPDATE authors SET link=? WHERE name=?',
                             (link, author.replace(',', '|')))
diff --git a/src/calibre/library/schema_upgrades.py b/src/calibre/library/schema_upgrades.py
index 8b4b6e6c83..47045156ef 100644
--- a/src/calibre/library/schema_upgrades.py
+++ b/src/calibre/library/schema_upgrades.py
@@ -9,7 +9,7 @@ __docformat__ = 'restructuredtext en'
 import os
 
 from calibre.utils.date import isoformat, DEFAULT_DATE
-from polyglot.builtins import iterkeys, itervalues, unicode_type
+from polyglot.builtins import itervalues, unicode_type
 
 
 class SchemaUpgrade(object):
@@ -590,7 +590,7 @@ class SchemaUpgrade(object):
                     custom_recipe_filename
             bdir = os.path.dirname(custom_recipes.file_path)
             for id_, title, script in recipes:
-                existing = frozenset(map(int, iterkeys(custom_recipes)))
+                existing = frozenset(map(int, custom_recipes))
                 if id_ in existing:
                     id_ = max(existing) + 1000
                 id_ = str(id_)
diff --git a/src/calibre/srv/ajax.py b/src/calibre/srv/ajax.py
index dd577408f5..f9d3b31b32 100644
--- a/src/calibre/srv/ajax.py
+++ b/src/calibre/srv/ajax.py
@@ -7,7 +7,7 @@ __license__ = 'GPL v3'
 __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
 
 from functools import partial
-from polyglot.builtins import iteritems, iterkeys, itervalues, unicode_type, zip, string_or_bytes
+from polyglot.builtins import iteritems, itervalues, unicode_type, zip, string_or_bytes
 from itertools import cycle
 
 from calibre import force_unicode
@@ -83,7 +83,7 @@ def book_to_json(ctx, rd, db, book_id,
             if mtime is not None:
                 v['mtime'] = isoformat(mtime, as_utc=True)
         data['format_metadata'] = mi.format_metadata
-        fmts = set(x.lower() for x in iterkeys(mi.format_metadata))
+        fmts = set(x.lower() for x in mi.format_metadata)
         pf = prefs['output_format'].lower()
         other_fmts = list(fmts)
         try:
diff --git a/src/calibre/srv/auto_reload.py b/src/calibre/srv/auto_reload.py
index 7051a540d8..4c0d3dbdf7 100644
--- a/src/calibre/srv/auto_reload.py
+++ b/src/calibre/srv/auto_reload.py
@@ -17,7 +17,7 @@ from calibre.srv.standalone import create_option_parser
 from calibre.srv.utils import create_sock_pair
 from calibre.srv.web_socket import DummyHandler
 from calibre.utils.monotonic import monotonic
-from polyglot.builtins import iterkeys, itervalues
+from polyglot.builtins import itervalues
 from polyglot.queue import Queue, Empty
 
 MAX_RETRIES = 10
@@ -76,7 +76,7 @@ if islinux:
 
         def loop(self):
             while True:
-                r = select.select([self.srv_sock] + list(iterkeys(self.fd_map)), [], [])[0]
+                r = select.select([self.srv_sock] + list(self.fd_map), [], [])[0]
                 modified = set()
                 for fd in r:
                     if fd is self.srv_sock:
diff --git a/src/calibre/srv/handler.py b/src/calibre/srv/handler.py
index d4ec69c111..abf609f404 100644
--- a/src/calibre/srv/handler.py
+++ b/src/calibre/srv/handler.py
@@ -15,7 +15,7 @@ from calibre.srv.routes import Router
 from calibre.srv.users import UserManager
 from calibre.utils.date import utcnow
 from calibre.utils.search_query_parser import ParseException
-from polyglot.builtins import iterkeys, itervalues
+from polyglot.builtins import itervalues
 
 
 class Context(object):
@@ -67,7 +67,7 @@ class Context(object):
         allowed_libraries = self.library_broker.allowed_libraries(lf)
         if not allowed_libraries:
             raise HTTPForbidden('The user {} is not allowed to access any libraries on this server'.format(request_data.username))
-        library_id = library_id or next(iterkeys(allowed_libraries))
+        library_id = library_id or next(iter(allowed_libraries))
         if library_id in allowed_libraries:
             return self.library_broker.get(library_id)
         raise HTTPForbidden('The user {} is not allowed to access the library {}'.format(request_data.username, library_id))
@@ -79,7 +79,7 @@ class Context(object):
         allowed_libraries = self.library_broker.allowed_libraries(lf)
         if not allowed_libraries:
             raise HTTPForbidden('The user {} is not allowed to access any libraries on this server'.format(request_data.username))
-        return dict(allowed_libraries), next(iterkeys(allowed_libraries))
+        return dict(allowed_libraries), next(iter(allowed_libraries))
 
     def restriction_for(self, request_data, db):
         return self.user_manager.library_restriction(request_data.username, path_for_db(db))
diff --git a/src/calibre/srv/library_broker.py b/src/calibre/srv/library_broker.py
index 6d02eb062e..1e5681d7a6 100644
--- a/src/calibre/srv/library_broker.py
+++ b/src/calibre/srv/library_broker.py
@@ -13,7 +13,7 @@ from calibre.db.cache import Cache
 from calibre.db.legacy import LibraryDatabase, create_backend, set_global_state
 from calibre.utils.filenames import samefile as _samefile
 from calibre.utils.monotonic import monotonic
-from polyglot.builtins import iteritems, iterkeys, itervalues
+from polyglot.builtins import iteritems, itervalues
 
 
 def canonicalize_path(p):
@@ -121,7 +121,7 @@ class LibraryBroker(object):
 
     @property
     def default_library(self):
-        return next(iterkeys(self.lmap))
+        return next(iter(self.lmap))
 
     @property
     def library_map(self):
diff --git a/src/calibre/srv/render_book.py b/src/calibre/srv/render_book.py
index 8f9a5cd7f6..c689a1c0de 100644
--- a/src/calibre/srv/render_book.py
+++ b/src/calibre/srv/render_book.py
@@ -27,7 +27,7 @@ from calibre.ebooks.oeb.polish.toc import get_toc, get_landmarks
 from calibre.ebooks.oeb.polish.utils import guess_type
 from calibre.utils.short_uuid import uuid4
 from calibre.utils.logging import default_log
-from polyglot.builtins import iteritems, iterkeys, map, unicode_type
+from polyglot.builtins import iteritems, map, unicode_type
 from polyglot.urllib import quote, urlparse
 
 RENDER_VERSION = 1
@@ -416,7 +416,7 @@ def map_epub_type(epub_type, attribs, elem):
         roles = OrderedDict([(k, True) for k in role.split()]) if role else OrderedDict()
         if val not in roles:
             roles[val] = True
-        role = ' '.join(iterkeys(roles))
+        role = ' '.join(roles)
         if in_attribs is None:
             attribs.append(['role', role])
         else:
diff --git a/src/calibre/srv/tests/ajax.py b/src/calibre/srv/tests/ajax.py
index af47b60d95..7707bd6d2b 100644
--- a/src/calibre/srv/tests/ajax.py
+++ b/src/calibre/srv/tests/ajax.py
@@ -13,7 +13,6 @@ from httplib import OK, NOT_FOUND, FORBIDDEN
 
 from calibre.ebooks.metadata.meta import get_metadata
 from calibre.srv.tests.base import LibraryBaseTest
-from polyglot.builtins import iterkeys
 from polyglot.urllib import urlencode, quote
 
 
@@ -46,12 +45,12 @@ class ContentTest(LibraryBaseTest):
             self.ae(request('/%s?id_is_uuid=true' % db.field_for('uuid', 1))[1], onedata)
 
             r, data = request('s')
-            self.ae(set(iterkeys(data)), set(map(str, db.all_book_ids())))
+            self.ae(set(data), set(map(str, db.all_book_ids())))
             r, zdata = request('s', headers={'Accept-Encoding':'gzip'})
             self.ae(r.getheader('Content-Encoding'), 'gzip')
             self.ae(json.loads(zlib.decompress(zdata, 16+zlib.MAX_WBITS)), data)
             r, data = request('s?ids=1,2')
-            self.ae(set(iterkeys(data)), {'1', '2'})
+            self.ae(set(data), {'1', '2'})
 
     # }}}
 
diff --git a/src/calibre/utils/date.py b/src/calibre/utils/date.py
index d125122707..0035c88dfb 100644
--- a/src/calibre/utils/date.py
+++ b/src/calibre/utils/date.py
@@ -14,7 +14,7 @@ from calibre import strftime
 from calibre.constants import iswindows, isosx, plugins, preferred_encoding
 from calibre.utils.iso8601 import utc_tz, local_tz, UNDEFINED_DATE
 from calibre.utils.localization import lcdata
-from polyglot.builtins import iterkeys, unicode_type
+from polyglot.builtins import unicode_type
 
 _utc_tz = utc_tz
 _local_tz = local_tz
@@ -478,7 +478,7 @@ def replace_months(datestr, clang):
     else:
         return datestr
 
-    for k in iterkeys(dictoen):
+    for k in dictoen:
         tmp = re.sub(k, dictoen[k], datestr)
         if tmp != datestr:
             break
diff --git a/src/calibre/utils/filenames.py b/src/calibre/utils/filenames.py
index 6c5ac38db8..7fc69c0123 100644
--- a/src/calibre/utils/filenames.py
+++ b/src/calibre/utils/filenames.py
@@ -14,7 +14,7 @@ from calibre.constants import (
     filesystem_encoding, iswindows, plugins, preferred_encoding, isosx
 )
 from calibre.utils.localization import get_udc
-from polyglot.builtins import iteritems, iterkeys, itervalues, unicode_type, range
+from polyglot.builtins import iteritems, itervalues, unicode_type, range
 
 
 def ascii_text(orig):
@@ -467,7 +467,7 @@ class WindowsAtomicFolderMove(object):
 
     def delete_originals(self):
         import win32file
-        for path in iterkeys(self.handle_map):
+        for path in self.handle_map:
             win32file.DeleteFile(path)
         self.close_handles()
 
diff --git a/src/calibre/utils/fonts/sfnt/cmap.py b/src/calibre/utils/fonts/sfnt/cmap.py
index aff1f88267..cc6c8b6cd7 100644
--- a/src/calibre/utils/fonts/sfnt/cmap.py
+++ b/src/calibre/utils/fonts/sfnt/cmap.py
@@ -16,7 +16,7 @@ from collections import OrderedDict
 from calibre.utils.fonts.utils import read_bmp_prefix
 from calibre.utils.fonts.sfnt import UnknownTable, max_power_of_two
 from calibre.utils.fonts.sfnt.errors import UnsupportedFont
-from polyglot.builtins import iterkeys, range
+from polyglot.builtins import range
 
 
 def split_range(start_code, end_code, cmap):  # {{{
@@ -229,7 +229,7 @@ class CmapTable(UnknownTable):
     def set_character_map(self, cmap):
         self.version, self.num_tables = 0, 1
         fmt = b'>7H'
-        codes = sorted(iterkeys(cmap))
+        codes = sorted(cmap)
 
         if not codes:
             start_code = [0xffff]
diff --git a/src/calibre/utils/fonts/sfnt/container.py b/src/calibre/utils/fonts/sfnt/container.py
index d833ba023c..17d7c54d38 100644
--- a/src/calibre/utils/fonts/sfnt/container.py
+++ b/src/calibre/utils/fonts/sfnt/container.py
@@ -25,7 +25,6 @@ from calibre.utils.fonts.sfnt.cmap import CmapTable
 from calibre.utils.fonts.sfnt.kern import KernTable
 from calibre.utils.fonts.sfnt.gsub import GSUBTable
 from calibre.utils.fonts.sfnt.cff.table import CFFTable
-from polyglot.builtins import iterkeys
 
 # OpenType spec: http://www.microsoft.com/typography/otspec/otff.htm
 
@@ -84,13 +83,13 @@ class Sfnt(object):
 
     def __iter__(self):
         '''Iterate over the table tags in order.'''
-        for x in sorted(iterkeys(self.tables)):
+        for x in sorted(self.tables):
             yield x
         # Although the optimal order is not alphabetical, the OTF spec says
         # they should be alphabetical, so we stick with that. See
         # http://partners.adobe.com/public/developer/opentype/index_recs.html
         # for optimal order.
-        # keys = list(self.tables.iterkeys())
+        # keys = list(self.tables)
         # order = {x:i for i, x in enumerate((b'head', b'hhea', b'maxp', b'OS/2',
         #     b'hmtx', b'LTSH', b'VDMX', b'hdmx', b'cmap', b'fpgm', b'prep',
         #     b'cvt ', b'loca', b'glyf', b'CFF ', b'kern', b'name', b'post',
diff --git a/src/calibre/utils/fonts/sfnt/subset.py b/src/calibre/utils/fonts/sfnt/subset.py
index 51d3d485ce..388c3dd9a5 100644
--- a/src/calibre/utils/fonts/sfnt/subset.py
+++ b/src/calibre/utils/fonts/sfnt/subset.py
@@ -217,7 +217,7 @@ def print_stats(old_stats, new_stats):
     prints('='*80)
     old_total = sum(old_stats.itervalues())
     new_total = sum(new_stats.itervalues())
-    tables = sorted(old_stats.iterkeys(), key=lambda x:old_stats[x],
+    tables = sorted(old_stats, key=lambda x:old_stats[x],
             reverse=True)
     for table in tables:
         osz = old_stats[table]
diff --git a/src/calibre/web/feeds/recipes/collection.py b/src/calibre/web/feeds/recipes/collection.py
index d27b21af49..94b900c4ed 100644
--- a/src/calibre/web/feeds/recipes/collection.py
+++ b/src/calibre/web/feeds/recipes/collection.py
@@ -18,7 +18,7 @@ from calibre.constants import numeric_version
 from calibre.utils.iso8601 import parse_iso8601
 from calibre.utils.date import now as nowf, utcnow, local_tz, isoformat, EPOCH, UNDEFINED_DATE
 from calibre.utils.recycle_bin import delete_file
-from polyglot.builtins import iteritems, iterkeys, unicode_type
+from polyglot.builtins import iteritems, unicode_type
 
 NS = 'http://calibre-ebook.com/recipe_collection'
 E = ElementMaker(namespace=NS, nsmap={None:NS})
@@ -164,7 +164,7 @@ def add_custom_recipes(script_map):
     from calibre.web.feeds.recipes import custom_recipes, \
             custom_recipe_filename
     id_ = 1000
-    keys = tuple(map(int, iterkeys(custom_recipes)))
+    keys = tuple(map(int, custom_recipes))
     if keys:
         id_ = max(keys)+1
     bdir = os.path.dirname(custom_recipes.file_path)
diff --git a/src/polyglot/builtins.py b/src/polyglot/builtins.py
index 96c226b182..24c781e401 100644
--- a/src/polyglot/builtins.py
+++ b/src/polyglot/builtins.py
@@ -8,6 +8,11 @@ import sys
 
 is_py3 = sys.version_info.major >= 3
 
+
+def iterkeys(d):
+    return iter(d)
+
+
 if is_py3:
     def reraise(tp, value, tb=None):
         try:
@@ -38,9 +43,6 @@ if is_py3:
     def itervalues(d):
         return iter(d.values())
 
-    def iterkeys(d):
-        return iter(d)
-
     def environ_item(x):
         if isinstance(x, bytes):
             x = x.decode('utf-8')
@@ -65,9 +67,6 @@ else:
     def iteritems(d):
         return d.iteritems()
 
-    def iterkeys(d):
-        return d.iterkeys()
-
     def itervalues(d):
         return d.itervalues()
 
diff --git a/src/tinycss/__init__.py b/src/tinycss/__init__.py
index 10827136ea..73451baf94 100644
--- a/src/tinycss/__init__.py
+++ b/src/tinycss/__init__.py
@@ -17,8 +17,6 @@ from tinycss.page3 import CSSPage3Parser
 from tinycss.fonts3 import CSSFonts3Parser
 from tinycss.media3 import CSSMedia3Parser
 
-from polyglot.builtins import iterkeys
-
 
 PARSER_MODULES = {
     'page3': CSSPage3Parser,
@@ -50,5 +48,5 @@ def make_parser(*features, **kwargs):
 
 def make_full_parser(**kwargs):
     ''' A parser that parses all supported CSS 3 modules in addition to CSS 2.1 '''
-    features = tuple(iterkeys(PARSER_MODULES))
+    features = tuple(PARSER_MODULES)
     return make_parser(*features, **kwargs)