diff --git a/src/calibre/db/cli/cmd_list.py b/src/calibre/db/cli/cmd_list.py
index 2ca97ee016..ecd0143af6 100644
--- a/src/calibre/db/cli/cmd_list.py
+++ b/src/calibre/db/cli/cmd_list.py
@@ -120,16 +120,15 @@ def as_machine_data(book_ids, data, metadata):
 
 def prepare_output_table(fields, book_ids, data, metadata):
     ans = []
-    u = type('')
     for book_id in book_ids:
         row = []
         ans.append(row)
         for field in fields:
             if field == 'id':
-                row.append(u(book_id))
+                row.append(unicode_type(book_id))
                 continue
             val = data.get(field.replace('*', '#'), {}).get(book_id)
-            row.append(u(val).replace('\n', ' '))
+            row.append(unicode_type(val).replace('\n', ' '))
     return ans
 
 
diff --git a/src/calibre/db/tests/legacy.py b/src/calibre/db/tests/legacy.py
index bfe9cf61a3..eac7c87194 100644
--- a/src/calibre/db/tests/legacy.py
+++ b/src/calibre/db/tests/legacy.py
@@ -12,7 +12,7 @@ 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, range, zip
+from polyglot.builtins import iteritems, range, unicode_type, zip
 from polyglot import reprlib
 
 # Utils {{{
@@ -116,7 +116,7 @@ class LegacyTest(BaseTest):
             for label, loc in iteritems(db.FIELD_MAP):
                 if isinstance(label, numbers.Integral):
                     label = '#'+db.custom_column_num_map[label]['label']
-                label = type('')(label)
+                label = unicode_type(label)
                 ans[label] = tuple(db.get_property(i, index_is_id=True, loc=loc)
                                    for i in db.all_ids())
                 if label in ('id', 'title', '#tags'):
@@ -282,7 +282,7 @@ class LegacyTest(BaseTest):
         old = db.get_data_as_dict(prefix='test-prefix')
         new = ndb.get_data_as_dict(prefix='test-prefix')
         for o, n in zip(old, new):
-            o = {type('')(k) if isinstance(k, bytes) else k:set(v) if isinstance(v, list) else v for k, v in iteritems(o)}
+            o = {unicode_type(k) if isinstance(k, bytes) else k:set(v) if isinstance(v, list) else v for k, v in iteritems(o)}
             n = {k:set(v) if isinstance(v, list) else v for k, v in iteritems(n)}
             self.assertEqual(o, n)
 
diff --git a/src/calibre/ebooks/docx/footnotes.py b/src/calibre/ebooks/docx/footnotes.py
index edb998f22c..a97d2a73e5 100644
--- a/src/calibre/ebooks/docx/footnotes.py
+++ b/src/calibre/ebooks/docx/footnotes.py
@@ -6,7 +6,7 @@ __license__ = 'GPL v3'
 __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
 from collections import OrderedDict
-from polyglot.builtins import iteritems
+from polyglot.builtins import iteritems, unicode_type
 
 
 class Note(object):
@@ -52,8 +52,8 @@ class Footnotes(object):
         if note is not None and note.type == 'normal':
             self.counter += 1
             anchor = 'note_%d' % self.counter
-            self.notes[anchor] = (type('')(self.counter), note)
-            return anchor, type('')(self.counter)
+            self.notes[anchor] = (unicode_type(self.counter), note)
+            return anchor, unicode_type(self.counter)
         return None, None
 
     def __iter__(self):
diff --git a/src/calibre/ebooks/docx/tables.py b/src/calibre/ebooks/docx/tables.py
index fa2ae28199..6f537e6daf 100644
--- a/src/calibre/ebooks/docx/tables.py
+++ b/src/calibre/ebooks/docx/tables.py
@@ -9,7 +9,7 @@ from lxml.html.builder import TABLE, TR, TD
 
 from calibre.ebooks.docx.block_styles import inherit, read_shd as rs, read_border, binary_property, border_props, ParagraphStyle, border_to_css
 from calibre.ebooks.docx.char_styles import RunStyle
-from polyglot.builtins import iteritems, itervalues, range, filter
+from polyglot.builtins import filter, iteritems, itervalues, range, unicode_type
 
 # Read from XML {{{
 read_shd = rs
@@ -646,9 +646,9 @@ class Table(object):
                 td = TD()
                 style_map[td] = s = self.style_map[tc]
                 if s.col_span is not inherit:
-                    td.set('colspan', type('')(s.col_span))
+                    td.set('colspan', unicode_type(s.col_span))
                 if s.row_span is not inherit:
-                    td.set('rowspan', type('')(s.row_span))
+                    td.set('rowspan', unicode_type(s.row_span))
                 td.tail = '\n\t\t\t'
                 tr.append(td)
                 for x in self.namespace.XPath('./w:p|./w:tbl')(tc):
diff --git a/src/calibre/ebooks/docx/writer/from_html.py b/src/calibre/ebooks/docx/writer/from_html.py
index a29ecef2f4..b0135fc839 100644
--- a/src/calibre/ebooks/docx/writer/from_html.py
+++ b/src/calibre/ebooks/docx/writer/from_html.py
@@ -128,7 +128,7 @@ class TextRun(object):
     def style_weight(self):
         ans = 0
         for text, preserve_whitespace, bookmark in self.texts:
-            if isinstance(text, type('')):
+            if isinstance(text, unicode_type):
                 ans += len(text)
         return ans
 
diff --git a/src/calibre/ebooks/metadata/author_mapper.py b/src/calibre/ebooks/metadata/author_mapper.py
index 9db1742a2c..30cbf1df46 100644
--- a/src/calibre/ebooks/metadata/author_mapper.py
+++ b/src/calibre/ebooks/metadata/author_mapper.py
@@ -1,14 +1,13 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 import re
 from collections import deque
 
 from calibre.utils.icu import capitalize, lower, upper
-from polyglot.builtins import filter
+from polyglot.builtins import filter, unicode_type
 
 
 def cap_author_token(token):
@@ -162,9 +161,9 @@ def find_tests():
             def run(rules, authors, expected):
                 if isinstance(rules, dict):
                     rules = [rules]
-                if isinstance(authors, type('')):
+                if isinstance(authors, unicode_type):
                     authors = [x.strip() for x in authors.split('&')]
-                if isinstance(expected, type('')):
+                if isinstance(expected, unicode_type):
                     expected = [x.strip() for x in expected.split('&')]
                 ans = map_authors(authors, compile_rules(rules))
                 self.assertEqual(ans, expected)
diff --git a/src/calibre/ebooks/metadata/tag_mapper.py b/src/calibre/ebooks/metadata/tag_mapper.py
index cd055791a4..b1a03b0a41 100644
--- a/src/calibre/ebooks/metadata/tag_mapper.py
+++ b/src/calibre/ebooks/metadata/tag_mapper.py
@@ -1,10 +1,11 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
+
 from collections import deque
-from polyglot.builtins import filter
+
+from polyglot.builtins import filter, unicode_type
 
 
 def compile_pat(pat):
@@ -144,9 +145,9 @@ def find_tests():
             def run(rules, tags, expected):
                 if isinstance(rules, dict):
                     rules = [rules]
-                if isinstance(tags, type('')):
+                if isinstance(tags, unicode_type):
                     tags = [x.strip() for x in tags.split(',')]
-                if isinstance(expected, type('')):
+                if isinstance(expected, unicode_type):
                     expected = [x.strip() for x in expected.split(',')]
                 ans = map_tags(tags, rules)
                 self.assertEqual(ans, expected)
diff --git a/src/calibre/ebooks/oeb/polish/cascade.py b/src/calibre/ebooks/oeb/polish/cascade.py
index c406b34e67..39797af130 100644
--- a/src/calibre/ebooks/oeb/polish/cascade.py
+++ b/src/calibre/ebooks/oeb/polish/cascade.py
@@ -18,7 +18,7 @@ from calibre.ebooks.oeb.base import OEB_STYLES, XHTML, css_text
 from calibre.ebooks.oeb.normalize_css import normalizers, DEFAULTS
 from calibre.ebooks.oeb.stylizer import media_ok, INHERITED
 from tinycss.fonts3 import serialize_font_family, parse_font_family
-from polyglot.builtins import iteritems, itervalues
+from polyglot.builtins import iteritems, itervalues, unicode_type
 
 _html_css_stylesheet = None
 
@@ -233,8 +233,7 @@ _defvals = None
 def defvals():
     global _defvals
     if _defvals is None:
-        u = type('')
-        _defvals = {k:Values(Property(k, u(val)).propertyValue) for k, val in iteritems(DEFAULTS)}
+        _defvals = {k:Values(Property(k, unicode_type(val)).propertyValue) for k, val in iteritems(DEFAULTS)}
     return _defvals
 
 
diff --git a/src/calibre/ebooks/oeb/polish/check/parsing.py b/src/calibre/ebooks/oeb/polish/check/parsing.py
index 8f70a441a1..34c24372a5 100644
--- a/src/calibre/ebooks/oeb/polish/check/parsing.py
+++ b/src/calibre/ebooks/oeb/polish/check/parsing.py
@@ -203,7 +203,7 @@ class NonUTF8(BaseError):
 
     def __call__(self, container):
         raw = container.raw_data(self.name)
-        if isinstance(raw, type('')):
+        if isinstance(raw, unicode_type):
             raw, changed = replace_encoding_declarations(raw)
             if changed:
                 container.open(self.name, 'wb').write(raw.encode('utf-8'))
diff --git a/src/calibre/ebooks/oeb/polish/container.py b/src/calibre/ebooks/oeb/polish/container.py
index 1d7b5ffca0..69beea9393 100644
--- a/src/calibre/ebooks/oeb/polish/container.py
+++ b/src/calibre/ebooks/oeb/polish/container.py
@@ -14,7 +14,6 @@ import time
 import unicodedata
 import uuid
 from collections import defaultdict
-from polyglot.builtins import iteritems, unicode_type, zip, map
 from io import BytesIO
 from itertools import count
 
@@ -54,6 +53,7 @@ from calibre.utils.filenames import hardlink_file, nlinks_file
 from calibre.utils.ipc.simple_worker import WorkerError, fork_job
 from calibre.utils.logging import default_log
 from calibre.utils.zipfile import ZipFile
+from polyglot.builtins import iteritems, map, unicode_type, zip
 from polyglot.urllib import urlparse
 
 exists, join, relpath = os.path.exists, os.path.join, os.path.relpath
@@ -672,7 +672,7 @@ class Container(ContainerBase):  # {{{
         ''' The names of all manifest items whose media-type matches predicate.
         `predicate` can be a set, a list, a string or a function taking a single
         argument, which will be called with the media-type. '''
-        if isinstance(predicate, type('')):
+        if isinstance(predicate, unicode_type):
             predicate = predicate.__eq__
         elif hasattr(predicate, '__contains__'):
             predicate = predicate.__contains__
diff --git a/src/calibre/ebooks/oeb/polish/split.py b/src/calibre/ebooks/oeb/polish/split.py
index 88ddeeec04..0fbb7065e7 100644
--- a/src/calibre/ebooks/oeb/polish/split.py
+++ b/src/calibre/ebooks/oeb/polish/split.py
@@ -184,7 +184,7 @@ def split(container, name, loc_or_xpath, before=True, totals=None):
     '''
 
     root = container.parsed(name)
-    if isinstance(loc_or_xpath, type('')):
+    if isinstance(loc_or_xpath, unicode_type):
         split_point = root.xpath(loc_or_xpath)[0]
     else:
         try:
diff --git a/src/calibre/ebooks/oeb/polish/stats.py b/src/calibre/ebooks/oeb/polish/stats.py
index c7a5d5c779..eb5aac053e 100644
--- a/src/calibre/ebooks/oeb/polish/stats.py
+++ b/src/calibre/ebooks/oeb/polish/stats.py
@@ -15,9 +15,8 @@ import regex
 from calibre.ebooks.oeb.base import XHTML, css_text
 from calibre.ebooks.oeb.polish.cascade import iterrules, resolve_styles, iterdeclaration
 from calibre.utils.icu import ord_string, safe_chr
-from polyglot.builtins import unicode_type
+from polyglot.builtins import iteritems, itervalues, range, unicode_type
 from tinycss.fonts3 import parse_font_family
-from polyglot.builtins import iteritems, itervalues, range
 
 
 def normalize_font_properties(font):
@@ -162,7 +161,7 @@ def get_font_dict(elem, resolve_property, pseudo=None):
     for p in 'weight', 'style', 'stretch':
         p = 'font-' + p
         rp = resolve_property(elem, p) if pseudo is None else resolve_property(elem, pseudo, p)
-        ans[p] = type('')(rp[0].value)
+        ans[p] = unicode_type(rp[0].value)
     normalize_font_properties(ans)
     return ans
 
diff --git a/src/calibre/ebooks/oeb/polish/tests/base.py b/src/calibre/ebooks/oeb/polish/tests/base.py
index 2b2b6d5b25..eb0e974f30 100644
--- a/src/calibre/ebooks/oeb/polish/tests/base.py
+++ b/src/calibre/ebooks/oeb/polish/tests/base.py
@@ -12,7 +12,7 @@ from calibre.ptempfile import TemporaryDirectory
 from calibre.ptempfile import PersistentTemporaryDirectory
 from calibre.utils.logging import DevNull
 import calibre.ebooks.oeb.polish.container as pc
-from polyglot.builtins import iteritems
+from polyglot.builtins import iteritems, unicode_type
 
 
 def get_cache():
@@ -24,7 +24,7 @@ def get_cache():
 
 
 def needs_recompile(obj, srcs):
-    if isinstance(srcs, type('')):
+    if isinstance(srcs, unicode_type):
         srcs = [srcs]
     try:
         obj_mtime = os.stat(obj).st_mtime
diff --git a/src/calibre/ebooks/oeb/polish/tests/cascade.py b/src/calibre/ebooks/oeb/polish/tests/cascade.py
index 60c4ead2d8..78ea976e2d 100644
--- a/src/calibre/ebooks/oeb/polish/tests/cascade.py
+++ b/src/calibre/ebooks/oeb/polish/tests/cascade.py
@@ -18,7 +18,7 @@ from calibre.ebooks.oeb.polish.container import ContainerBase, href_to_name
 from calibre.ebooks.oeb.polish.stats import StatsCollector, font_keys, normalize_font_properties, prepare_font_rule
 from calibre.ebooks.oeb.polish.tests.base import BaseTest
 from calibre.utils.logging import Log, Stream
-from polyglot.builtins import iteritems
+from polyglot.builtins import iteritems, unicode_type
 
 
 class VirtualContainer(ContainerBase):
@@ -83,7 +83,7 @@ class CascadeTest(BaseTest):
             elem = next(select(selector))
             ans = resolve_property(elem, name)
             if val is None:
-                val = type('')(DEFAULTS[name])
+                val = unicode_type(DEFAULTS[name])
             self.assertEqual(val, ans.cssText)
 
         def test_pseudo_property(select, resolve_pseudo_property, selector, prop, name, val=None, abort_on_missing=False):
@@ -94,7 +94,7 @@ class CascadeTest(BaseTest):
                     self.assertTrue(ans is None)
                     return
             if val is None:
-                val = type('')(DEFAULTS[name])
+                val = unicode_type(DEFAULTS[name])
             self.assertEqual(val, ans.cssText)
 
         def get_maps(html, styles=None, pseudo=False):
diff --git a/src/calibre/ebooks/oeb/polish/tests/structure.py b/src/calibre/ebooks/oeb/polish/tests/structure.py
index 6029eba71f..a2a04bae7d 100644
--- a/src/calibre/ebooks/oeb/polish/tests/structure.py
+++ b/src/calibre/ebooks/oeb/polish/tests/structure.py
@@ -64,7 +64,7 @@ def create_epub(manifest, spine=(), guide=(), meta_cover=None, ver=3):
 </container>''')
         zf.writestr('content.opf', opf.encode('utf-8'))
         for name, data, properties in manifest:
-            if isinstance(data, type('')):
+            if isinstance(data, unicode_type):
                 data = data.encode('utf-8')
             zf.writestr(name, data)
     buf.seek(0)
diff --git a/src/calibre/ebooks/pdf/render/toc.py b/src/calibre/ebooks/pdf/render/toc.py
index 6ab18a6dd3..29f7479b7a 100644
--- a/src/calibre/ebooks/pdf/render/toc.py
+++ b/src/calibre/ebooks/pdf/render/toc.py
@@ -9,7 +9,8 @@ import os
 
 from lxml.html import tostring
 from lxml.html.builder import (HTML, HEAD, BODY, TABLE, TR, TD, H2, STYLE)
-from polyglot.builtins import range
+
+from polyglot.builtins import range, unicode_type
 
 
 def calculate_page_number(num, map_expression, evaljs):
@@ -36,7 +37,7 @@ def convert_node(toc, table, level, pdf, pdf_page_number_map, evaljs):
     a = anchors[path]
     dest = a.get(frag, a[None])
     num = calculate_page_number(pdf.page_tree.obj.get_num(dest[0]), pdf_page_number_map, evaljs)
-    tr[1].text = type('')(num)
+    tr[1].text = unicode_type(num)
     table.append(tr)
 
 
diff --git a/src/calibre/gui2/icon_theme.py b/src/calibre/gui2/icon_theme.py
index c987cb8c81..59d97928c3 100644
--- a/src/calibre/gui2/icon_theme.py
+++ b/src/calibre/gui2/icon_theme.py
@@ -613,7 +613,7 @@ class ChooseTheme(Dialog):
         w.l = l = QGridLayout(w)
 
         def add_row(x, y=None):
-            if isinstance(x, type('')):
+            if isinstance(x, unicode_type):
                 x = QLabel(x)
             row = l.rowCount()
             if y is None:
diff --git a/src/calibre/gui2/open_with.py b/src/calibre/gui2/open_with.py
index dc55efe393..8eed3f1757 100644
--- a/src/calibre/gui2/open_with.py
+++ b/src/calibre/gui2/open_with.py
@@ -21,7 +21,7 @@ from calibre.gui2.widgets2 import Dialog
 from calibre.gui2.progress_indicator import ProgressIndicator
 from calibre.utils.config import JSONConfig
 from calibre.utils.icu import numeric_sort_key as sort_key
-from polyglot.builtins import iteritems, string_or_bytes, range
+from polyglot.builtins import iteritems, string_or_bytes, range, unicode_type
 
 ENTRY_ROLE = Qt.UserRole
 
@@ -324,7 +324,7 @@ def choose_program(file_type='jpeg', parent=None, prefs=oprefs):
     entry = choose_manually(file_type, parent) if d.select_manually else d.selected_entry
     if entry is not None:
         entry = finalize_entry(entry)
-        entry['uuid'] = type('')(uuid.uuid4())
+        entry['uuid'] = unicode_type(uuid.uuid4())
         entries = oprefs['entries']
         if oft not in entries:
             entries[oft] = []
diff --git a/src/calibre/gui2/tweak_book/boss.py b/src/calibre/gui2/tweak_book/boss.py
index 5856c50182..9d01a235ef 100644
--- a/src/calibre/gui2/tweak_book/boss.py
+++ b/src/calibre/gui2/tweak_book/boss.py
@@ -69,7 +69,7 @@ from calibre.utils.config import JSONConfig
 from calibre.utils.icu import numeric_sort_key
 from calibre.utils.imghdr import identify
 from calibre.utils.tdir_in_cache import tdir_in_cache
-from polyglot.builtins import iteritems, itervalues, string_or_bytes, map
+from polyglot.builtins import iteritems, itervalues, string_or_bytes, map, unicode_type
 from polyglot.urllib import urlparse
 
 _diff_dialogs = []
@@ -376,7 +376,7 @@ class Boss(QObject):
                     import traceback
                     traceback.print_exc()
             if ef:
-                if isinstance(ef, type('')):
+                if isinstance(ef, unicode_type):
                     ef = [ef]
                 tuple(map(self.gui.file_list.request_edit, ef))
             else:
diff --git a/src/calibre/gui2/tweak_book/completion/basic.py b/src/calibre/gui2/tweak_book/completion/basic.py
index 503a67eaf5..a40d88a2ac 100644
--- a/src/calibre/gui2/tweak_book/completion/basic.py
+++ b/src/calibre/gui2/tweak_book/completion/basic.py
@@ -112,7 +112,7 @@ def create_anchor_map(root):
 def complete_anchor(name, data_conn):
     if name not in file_cache:
         data = raw = get_data(data_conn, 'file_data', name)
-        if isinstance(raw, type('')):
+        if isinstance(raw, unicode_type):
             try:
                 root = parse(raw, decoder=lambda x:x.decode('utf-8'))
             except Exception:
diff --git a/src/calibre/gui2/tweak_book/diff/view.py b/src/calibre/gui2/tweak_book/diff/view.py
index 8c9e9c5f5b..7fb2389cc4 100644
--- a/src/calibre/gui2/tweak_book/diff/view.py
+++ b/src/calibre/gui2/tweak_book/diff/view.py
@@ -528,7 +528,7 @@ class DiffSplit(QSplitter):  # {{{
     def add_diff(self, left_name, right_name, left_text, right_text, context=None, syntax=None, beautify=False):
         left_text, right_text = left_text or '', right_text or ''
         is_identical = len(left_text) == len(right_text) and left_text == right_text and left_name == right_name
-        is_text = isinstance(left_text, type('')) and isinstance(right_text, type(''))
+        is_text = isinstance(left_text, unicode_type) and isinstance(right_text, unicode_type)
         left_name = left_name or '[%s]'%_('This file was added')
         right_name = right_name or '[%s]'%_('This file was removed')
         self.left.headers.append((self.left.blockCount() - 1, left_name))
diff --git a/src/calibre/gui2/tweak_book/editor/snippets.py b/src/calibre/gui2/tweak_book/editor/snippets.py
index 06f76a90ed..a6ddf05f1f 100644
--- a/src/calibre/gui2/tweak_book/editor/snippets.py
+++ b/src/calibre/gui2/tweak_book/editor/snippets.py
@@ -173,7 +173,7 @@ def snippets(refresh=False):
     if _snippets is None or refresh:
         _snippets = copy.deepcopy(builtin_snippets)
         for snip in user_snippets.get('snippets', []):
-            if snip['trigger'] and isinstance(snip['trigger'], type('')):
+            if snip['trigger'] and isinstance(snip['trigger'], unicode_type):
                 key = snip_key(snip['trigger'], *snip['syntaxes'])
                 _snippets[key] = {'template':snip['template'], 'description':snip['description']}
         _snippets = sorted(iteritems(_snippets), key=(lambda key_snip:string_length(key_snip[0].trigger)), reverse=True)
diff --git a/src/calibre/gui2/tweak_book/manage_fonts.py b/src/calibre/gui2/tweak_book/manage_fonts.py
index 0cf97741a0..236ca44edb 100644
--- a/src/calibre/gui2/tweak_book/manage_fonts.py
+++ b/src/calibre/gui2/tweak_book/manage_fonts.py
@@ -66,11 +66,11 @@ class EmbeddingData(Dialog):
             text.append('<li style="margin-bottom:2em">' + '<b>' + face['path'] + '</b>')
             name = face.get('full_name') or face.get('family_name') or face.get('subfamily_name')
             if name:
-                text.append('<br>' + _('Name:') + '\xa0<b>' + type('')(name) + '</b>')
+                text.append('<br>' + _('Name:') + '\xa0<b>' + unicode_type(name) + '</b>')
             if 'font-weight' in face:
-                text.append('<br>' + 'font-weight:\xa0' + type('')(face['font-weight']))
+                text.append('<br>' + 'font-weight:\xa0' + unicode_type(face['font-weight']))
             if 'font-style' in face:
-                text.append('<br>' + 'font-style:\xa0' + type('')(face['font-style']))
+                text.append('<br>' + 'font-style:\xa0' + unicode_type(face['font-style']))
         self.text.setHtml('\n'.join(text))
 
 
diff --git a/src/calibre/gui2/tweak_book/preview.py b/src/calibre/gui2/tweak_book/preview.py
index b4084f639f..f86a8fa6bd 100644
--- a/src/calibre/gui2/tweak_book/preview.py
+++ b/src/calibre/gui2/tweak_book/preview.py
@@ -166,7 +166,7 @@ class NetworkReply(QNetworkReply):
             QTimer.singleShot(0, self.check_for_parse)
         else:
             data = get_data(name)
-            if isinstance(data, type('')):
+            if isinstance(data, unicode_type):
                 data = data.encode('utf-8')
                 mime_type += '; charset=utf-8'
             self.__data = data
diff --git a/src/calibre/gui2/tweak_book/reports.py b/src/calibre/gui2/tweak_book/reports.py
index 19e3b5b2f5..df729f5844 100644
--- a/src/calibre/gui2/tweak_book/reports.py
+++ b/src/calibre/gui2/tweak_book/reports.py
@@ -265,7 +265,7 @@ class FilesModel(FileCollection):
                 return entry.basename
             if col == 2:
                 sz = entry.size / 1024.
-                return ('%.2f' % sz if int(sz) != sz else type('')(sz))
+                return ('%.2f' % sz if int(sz) != sz else unicode_type(sz))
             if col == 3:
                 return self.CATEGORY_NAMES.get(entry.category)
 
@@ -447,9 +447,9 @@ class ImagesModel(FileCollection):
                 return entry.basename
             if col == 1:
                 sz = entry.size / 1024.
-                return ('%.2f' % sz if int(sz) != sz else type('')(sz))
+                return ('%.2f' % sz if int(sz) != sz else unicode_type(sz))
             if col == 2:
-                return type('')(len(entry.usage))
+                return unicode_type(len(entry.usage))
             if col == 3:
                 return '%d x %d' % (entry.width, entry.height)
         elif role == Qt.UserRole:
@@ -713,7 +713,7 @@ class WordsModel(FileCollection):
                     ans += ' (%s)' % entry.locale.countrycode
                 return ans
             if col == 2:
-                return type('')(len(entry.usage))
+                return unicode_type(len(entry.usage))
         elif role == Qt.UserRole:
             try:
                 return self.files[index.row()]
@@ -802,7 +802,7 @@ class CharsModel(FileCollection):
             if col == 2:
                 return ('U+%04X' if entry.codepoint < 0x10000 else 'U+%06X') % entry.codepoint
             if col == 3:
-                return type('')(entry.count)
+                return unicode_type(entry.count)
         elif role == Qt.UserRole:
             try:
                 return self.files[index.row()]
diff --git a/src/calibre/gui2/tweak_book/ui.py b/src/calibre/gui2/tweak_book/ui.py
index 89a6f4fa3d..cc358debf7 100644
--- a/src/calibre/gui2/tweak_book/ui.py
+++ b/src/calibre/gui2/tweak_book/ui.py
@@ -320,7 +320,7 @@ class Main(MainWindow):
                 toolbar_actions[sid] = ac
             if target is not None:
                 ac.triggered.connect(target)
-            if isinstance(keys, type('')):
+            if isinstance(keys, unicode_type):
                 keys = (keys,)
             self.keyboard.register_shortcut(
                 sid, unicode_type(ac.text()).replace('&', ''), default_keys=keys, description=description, action=ac, group=group)
diff --git a/src/calibre/gui2/win_file_dialogs.py b/src/calibre/gui2/win_file_dialogs.py
index b4e93a7331..e718250ddf 100644
--- a/src/calibre/gui2/win_file_dialogs.py
+++ b/src/calibre/gui2/win_file_dialogs.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
+
 import sys, subprocess, struct, os
 from threading import Thread
 from uuid import uuid4
@@ -59,7 +59,7 @@ def serialize_binary(key, val):
 
 def serialize_string(key, val):
     key = key.encode('ascii') if not isinstance(key, bytes) else key
-    val = type('')(val).encode('utf-8')
+    val = unicode_type(val).encode('utf-8')
     if len(val) > 2**16 - 1:
         raise ValueError('%s is too long' % key)
     return struct.pack(b'=B%dsH%ds' % (len(key), len(val)), len(key), key, len(val), val)
@@ -198,7 +198,7 @@ def run_file_dialog(
     from calibre import prints
     from calibre.constants import DEBUG
     if DEBUG:
-        prints('stdout+stderr from file dialog helper:', type('')([h.stdoutdata, h.stderrdata]))
+        prints('stdout+stderr from file dialog helper:', unicode_type([h.stdoutdata, h.stderrdata]))
 
     if h.rc != 0:
         raise Exception('File dialog failed (return code %s): %s' % (h.rc, get_errors()))
@@ -211,7 +211,7 @@ def run_file_dialog(
         return ()
     parts = list(filter(None, server.data.split(b'\0')))
     if DEBUG:
-        prints('piped data from file dialog helper:', type('')(parts))
+        prints('piped data from file dialog helper:', unicode_type(parts))
     if len(parts) < 2:
         return ()
     if parts[0] != secret:
@@ -310,7 +310,7 @@ class PipeServer(Thread):
 
         def as_unicode(err):
             try:
-                self.err_msg = type('')(err)
+                self.err_msg = unicode_type(err)
             except Exception:
                 self.err_msg = repr(err)
         try:
diff --git a/src/calibre/srv/handler.py b/src/calibre/srv/handler.py
index 5e536fbb57..f06b1416ad 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 itervalues, filter
+from polyglot.builtins import itervalues, filter, unicode_type
 
 
 class Context(object):
@@ -148,7 +148,7 @@ class Context(object):
             if old is None or old[0] <= db.last_modified():
                 categories = db.get_categories(book_ids=restrict_to_ids, sort=opts.sort_by, first_letter_sort=opts.collapse_model == 'first letter')
                 data = json.dumps(render(db, categories), ensure_ascii=False)
-                if isinstance(data, type('')):
+                if isinstance(data, unicode_type):
                     data = data.encode('utf-8')
                 cache[key] = old = (utcnow(), data)
                 if len(cache) > self.CATEGORY_CACHE_SIZE:
diff --git a/src/calibre/srv/loop.py b/src/calibre/srv/loop.py
index 2a037eeca9..9fb7cee62b 100644
--- a/src/calibre/srv/loop.py
+++ b/src/calibre/srv/loop.py
@@ -23,7 +23,7 @@ from calibre.utils.socket_inheritance import set_socket_inherit
 from calibre.utils.logging import ThreadSafeLog
 from calibre.utils.monotonic import monotonic
 from calibre.utils.mdns import get_external_ip
-from polyglot.builtins import iteritems
+from polyglot.builtins import iteritems, unicode_type
 from polyglot.queue import Empty, Full
 
 READ, WRITE, RDWR, WAIT = 'READ', 'WRITE', 'RDWR', 'WAIT'
@@ -451,7 +451,7 @@ class ServerLoop(object):
         self.socket.listen(min(socket.SOMAXCONN, 128))
         self.bound_address = ba = self.socket.getsockname()
         if isinstance(ba, tuple):
-            ba = ':'.join(map(type(''), ba))
+            ba = ':'.join(map(unicode_type, ba))
         self.pool.start()
         with TemporaryDirectory(prefix='srv-') as tdir:
             self.tdir = tdir
diff --git a/src/calibre/srv/routes.py b/src/calibre/srv/routes.py
index 1c2ace4b2a..e82384cb9c 100644
--- a/src/calibre/srv/routes.py
+++ b/src/calibre/srv/routes.py
@@ -143,7 +143,7 @@ class Route(object):
                     default = self.defaults[name] = eval(default)
                     if isinstance(default, numbers.Number):
                         self.type_checkers[name] = type(default)
-                    if is_sponge and not isinstance(default, type('')):
+                    if is_sponge and not isinstance(default, unicode_type):
                         raise route_error('Soak up path component must have a default value of string type')
                 else:
                     if found_optional_part is not False:
diff --git a/src/calibre/srv/tests/http.py b/src/calibre/srv/tests/http.py
index d6970721ed..25870faa37 100644
--- a/src/calibre/srv/tests/http.py
+++ b/src/calibre/srv/tests/http.py
@@ -353,25 +353,25 @@ class TestHTTP(BaseTest):
                 conn = server.connect()
                 conn.request('GET', '/test')
                 r = conn.getresponse()
-                etag = type('')(r.getheader('ETag'))
+                etag = unicode_type(r.getheader('ETag'))
                 self.assertTrue(etag)
                 self.ae(r.getheader('Content-Type'), guess_type(f.name)[0])
-                self.ae(type('')(r.getheader('Accept-Ranges')), 'bytes')
+                self.ae(unicode_type(r.getheader('Accept-Ranges')), 'bytes')
                 self.ae(int(r.getheader('Content-Length')), len(fdata))
                 self.ae(r.status, http_client.OK), self.ae(r.read(), fdata)
 
                 conn.request('GET', '/test', headers={'Range':'bytes=2-25'})
                 r = conn.getresponse()
                 self.ae(r.status, http_client.PARTIAL_CONTENT)
-                self.ae(type('')(r.getheader('Accept-Ranges')), 'bytes')
-                self.ae(type('')(r.getheader('Content-Range')), 'bytes 2-25/%d' % len(fdata))
+                self.ae(unicode_type(r.getheader('Accept-Ranges')), 'bytes')
+                self.ae(unicode_type(r.getheader('Content-Range')), 'bytes 2-25/%d' % len(fdata))
                 self.ae(int(r.getheader('Content-Length')), 24)
                 self.ae(r.read(), fdata[2:26])
 
                 conn.request('GET', '/test', headers={'Range':'bytes=100000-'})
                 r = conn.getresponse()
                 self.ae(r.status, http_client.REQUESTED_RANGE_NOT_SATISFIABLE)
-                self.ae(type('')(r.getheader('Content-Range')), 'bytes */%d' % len(fdata))
+                self.ae(unicode_type(r.getheader('Content-Range')), 'bytes */%d' % len(fdata))
 
                 conn.request('GET', '/test', headers={'Range':'bytes=25-50', 'If-Range':etag})
                 r = conn.getresponse()
diff --git a/src/calibre/srv/tests/web_sockets.py b/src/calibre/srv/tests/web_sockets.py
index 20666c8e09..8197407f47 100644
--- a/src/calibre/srv/tests/web_sockets.py
+++ b/src/calibre/srv/tests/web_sockets.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
+
 import socket, os, struct, errno, numbers
 from collections import deque, namedtuple
 from functools import partial
@@ -132,7 +132,7 @@ class WSClient(object):
     def write_message(self, msg, chunk_size=None):
         if isinstance(msg, tuple):
             opcode, msg = msg
-            if isinstance(msg, type('')):
+            if isinstance(msg, unicode_type):
                 msg = msg.encode('utf-8')
             return self.write_frame(1, opcode, msg)
         w = MessageWriter(msg, self.mask, chunk_size)
@@ -147,7 +147,7 @@ class WSClient(object):
         self.socket.sendall(frame)
 
     def write_close(self, code, reason=b''):
-        if isinstance(reason, type('')):
+        if isinstance(reason, unicode_type):
             reason = reason.encode('utf-8')
         self.write_frame(1, CLOSE, struct.pack(b'!H', code) + reason)
 
diff --git a/src/calibre/srv/utils.py b/src/calibre/srv/utils.py
index 8d3f65eb56..86abd14f6b 100644
--- a/src/calibre/srv/utils.py
+++ b/src/calibre/srv/utils.py
@@ -32,7 +32,7 @@ encode_name, decode_name
 
 
 def http_date(timeval=None):
-    return type('')(formatdate(timeval=timeval, usegmt=True))
+    return unicode_type(formatdate(timeval=timeval, usegmt=True))
 
 
 class MultiDict(dict):  # {{{
diff --git a/src/calibre/srv/web_socket.py b/src/calibre/srv/web_socket.py
index 60f35eb75a..dcb5d74e74 100644
--- a/src/calibre/srv/web_socket.py
+++ b/src/calibre/srv/web_socket.py
@@ -21,6 +21,7 @@ from calibre.srv.loop import (
 from calibre.srv.utils import DESIRED_SEND_BUFFER_SIZE
 from calibre.utils.speedups import ReadOnlyFileBuffer
 from polyglot import http_client
+from polylot.builtins import unicode_type
 from polyglot.binary import as_base64_unicode
 from polyglot.queue import Empty, Queue
 
@@ -184,7 +185,7 @@ class ReadFrame(object):  # {{{
 
 
 def create_frame(fin, opcode, payload, mask=None, rsv=0):
-    if isinstance(payload, type('')):
+    if isinstance(payload, unicode_type):
         payload = payload.encode('utf-8')
     l = len(payload)
     header_len = 2 + (0 if l < 126 else 2 if 126 <= l <= 65535 else 8) + (0 if mask is None else 4)
@@ -213,7 +214,7 @@ class MessageWriter(object):
 
     def __init__(self, buf, mask=None, chunk_size=None):
         self.buf, self.data_type, self.mask = buf, BINARY, mask
-        if isinstance(buf, type('')):
+        if isinstance(buf, unicode_type):
             self.buf, self.data_type = ReadOnlyFileBuffer(buf.encode('utf-8')), TEXT
         elif isinstance(buf, bytes):
             self.buf = ReadOnlyFileBuffer(buf)
@@ -428,7 +429,7 @@ class WebSocketConnection(HTTPConnection):
         self.set_ws_state()
 
     def websocket_close(self, code=NORMAL_CLOSE, reason=b''):
-        if isinstance(reason, type('')):
+        if isinstance(reason, unicode_type):
             reason = reason.encode('utf-8')
         self.stop_reading = True
         reason = reason[:123]
@@ -493,7 +494,7 @@ class WebSocketConnection(HTTPConnection):
         ''' Useful for streaming handlers that want to break up messages into
         frames themselves. Note that these frames will be interleaved with
         control frames, so they should not be too large. '''
-        opcode = (TEXT if isinstance(data, type('')) else BINARY) if is_first else CONTINUATION
+        opcode = (TEXT if isinstance(data, unicode_type) else BINARY) if is_first else CONTINUATION
         fin = 1 if is_last else 0
         frame = create_frame(fin, opcode, data)
         with self.cf_lock:
@@ -502,7 +503,7 @@ class WebSocketConnection(HTTPConnection):
     def send_websocket_ping(self, data=b''):
         ''' Send a PING to the remote client, it should reply with a PONG which
         will be sent to the handle_websocket_pong callback in your handler. '''
-        if isinstance(data, type('')):
+        if isinstance(data, unicode_type):
             data = data.encode('utf-8')
         frame = create_frame(True, PING, data)
         with self.cf_lock:
diff --git a/src/calibre/utils/exim.py b/src/calibre/utils/exim.py
index eab2fc8dcf..1687ec52d7 100644
--- a/src/calibre/utils/exim.py
+++ b/src/calibre/utils/exim.py
@@ -1,8 +1,8 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
+
 import os, json, struct, hashlib, sys, errno, tempfile, time, shutil, uuid
 from collections import Counter
 
@@ -25,7 +25,7 @@ def send_file(from_obj, to_obj, chunksize=1<<20):
             break
         m.update(raw)
         to_obj.write(raw)
-    return type('')(m.hexdigest())
+    return unicode_type(m.hexdigest())
 
 
 class FileDest(object):
@@ -55,7 +55,7 @@ class FileDest(object):
     def close(self):
         if not self._discard:
             size = self.exporter.f.tell() - self.start_pos
-            digest = type('')(self.hasher.hexdigest())
+            digest = unicode_type(self.hasher.hexdigest())
             self.exporter.file_metadata[self.key] = (len(self.exporter.parts), self.start_pos, size, digest, self.mtime)
         del self.exporter, self.hasher
 
diff --git a/src/calibre/utils/img.py b/src/calibre/utils/img.py
index 9ae657d9c7..bf10b2b7af 100644
--- a/src/calibre/utils/img.py
+++ b/src/calibre/utils/img.py
@@ -1,7 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2015-2019, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 import errno
@@ -54,7 +53,7 @@ def get_exe_path(name):
 
 def load_jxr_data(data):
     with TemporaryDirectory() as tdir:
-        if iswindows and isinstance(tdir, type('')):
+        if iswindows and isinstance(tdir, unicode_type):
             tdir = tdir.encode('mbcs')
         with lopen(os.path.join(tdir, 'input.jxr'), 'wb') as f:
             f.write(data)
@@ -97,7 +96,7 @@ def image_from_path(path):
 
 def image_from_x(x):
     ' Create an image from a bytestring or a path or a file like object. '
-    if isinstance(x, type('')):
+    if isinstance(x, unicode_type):
         return image_from_path(x)
     if hasattr(x, 'read'):
         return image_from_data(x.read())
@@ -512,7 +511,7 @@ def run_optimizer(file_path, cmd, as_filter=False, input_data=None):
             # encodeable in mbcs, so we fail here, where it is more explicit,
             # instead.
             cmd = [x.encode('mbcs') if isinstance(x, unicode_type) else x for x in cmd]
-            if isinstance(cwd, type('')):
+            if isinstance(cwd, unicode_type):
                 cwd = cwd.encode('mbcs')
         stdin = subprocess.PIPE if as_filter else None
         stderr = subprocess.PIPE if as_filter else subprocess.STDOUT
diff --git a/src/calibre/utils/imghdr.py b/src/calibre/utils/imghdr.py
index 9ff016386b..fa6558dda0 100644
--- a/src/calibre/utils/imghdr.py
+++ b/src/calibre/utils/imghdr.py
@@ -1,13 +1,13 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
+
 from struct import unpack, error
 import os
 from calibre.utils.speedups import ReadOnlyFileBuffer
 from calibre.constants import ispy3
-from polyglot.builtins import string_or_bytes
+from polyglot.builtins import string_or_bytes, unicode_type
 
 """ Recognize image file formats and sizes based on their first few bytes."""
 
@@ -43,7 +43,7 @@ def identify(src):
     recognized. '''
     width = height = -1
 
-    if isinstance(src, type('')):
+    if isinstance(src, unicode_type):
         stream = lopen(src, 'rb')
     elif isinstance(src, bytes):
         stream = ReadOnlyFileBuffer(src)
diff --git a/src/calibre/utils/open_with/linux.py b/src/calibre/utils/open_with/linux.py
index f397c68659..b467522e20 100644
--- a/src/calibre/utils/open_with/linux.py
+++ b/src/calibre/utils/open_with/linux.py
@@ -13,7 +13,7 @@ from calibre.constants import filesystem_encoding, cache_dir
 from calibre.utils.icu import numeric_sort_key as sort_key
 from calibre.utils.localization import canonicalize_lang, get_lang
 from calibre.utils.serialize import msgpack_dumps, msgpack_loads
-from polyglot.builtins import iteritems, itervalues, string_or_bytes
+from polyglot.builtins import iteritems, itervalues, string_or_bytes, unicode_type
 
 
 def parse_localized_key(key):
@@ -66,7 +66,7 @@ def parse_desktop_file(path):
                     name, lang = parse_localized_key(k)
                     if name not in ans:
                         ans[name] = {}
-                    if isinstance(ans[name], type('')):
+                    if isinstance(ans[name], unicode_type):
                         ans[name] = {None:ans[name]}
                     ans[name][lang] = v
                 else:
diff --git a/src/calibre/utils/rapydscript.py b/src/calibre/utils/rapydscript.py
index bac9a32ab4..c5f71e7c3c 100644
--- a/src/calibre/utils/rapydscript.py
+++ b/src/calibre/utils/rapydscript.py
@@ -39,7 +39,7 @@ def update_rapydscript():
     base = d(d(d(d(d(abspath(__file__))))))
     base = os.path.join(base, 'rapydscript')
     raw = subprocess.check_output(['node', '--harmony', os.path.join(base, 'bin', 'export')])
-    if isinstance(raw, type('')):
+    if isinstance(raw, unicode_type):
         raw = raw.encode('utf-8')
     path = P(COMPILER_PATH, allow_user_override=False)
     with open(path, 'wb') as f:
@@ -273,7 +273,7 @@ def leading_whitespace(line):
 
 
 def format_error(data):
-    return ':'.join(map(type(''), (data['file'], data['line'], data['col'], data['message'])))
+    return ':'.join(map(unicode_type, (data['file'], data['line'], data['col'], data['message'])))
 
 
 class Repl(Thread):
diff --git a/src/calibre/utils/short_uuid.py b/src/calibre/utils/short_uuid.py
index 4aeeb48b52..0d8b40c7da 100644
--- a/src/calibre/utils/short_uuid.py
+++ b/src/calibre/utils/short_uuid.py
@@ -1,7 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
-
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 '''
@@ -10,6 +9,8 @@ Generate UUID encoded using a user specified alphabet.
 
 import string, math, uuid as _uuid
 
+from polyglot.builtins import unicode_type
+
 
 def num_to_string(number, alphabet, alphabet_len, pad_to_length=None):
     ans = []
@@ -35,7 +36,7 @@ class ShortUUID(object):
         # We do not include zero and one in the default alphabet as they can be
         # confused with the letters O and I in some fonts. And removing them
         # does not change the uuid_pad_len.
-        self.alphabet = tuple(sorted(type('')(alphabet or (string.digits + string.ascii_letters)[2:])))
+        self.alphabet = tuple(sorted(unicode_type(alphabet or (string.digits + string.ascii_letters)[2:])))
         self.alphabet_len = len(self.alphabet)
         self.alphabet_map = {c:i for i, c in enumerate(self.alphabet)}
         self.uuid_pad_len = int(math.ceil(math.log(1 << 128, self.alphabet_len)))
diff --git a/src/calibre/utils/winreg/lib.py b/src/calibre/utils/winreg/lib.py
index f96ecd630d..57f382b480 100644
--- a/src/calibre/utils/winreg/lib.py
+++ b/src/calibre/utils/winreg/lib.py
@@ -8,6 +8,8 @@ __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
 import ctypes, ctypes.wintypes as types, struct, datetime, numbers
 import winerror, win32con
 
+from polyglot.builtins import unicode_type
+
 try:
     import winreg
 except ImportError:
@@ -111,11 +113,11 @@ def expand_environment_strings(src):
 def convert_to_registry_data(value, has_expansions=False):
     if value is None:
         return None, winreg.REG_NONE, 0
-    if isinstance(value, (type(''), bytes)):
+    if isinstance(value, (unicode_type, bytes)):
         buf = ctypes.create_unicode_buffer(value)
         return buf, (winreg.REG_EXPAND_SZ if has_expansions else winreg.REG_SZ), len(buf) * 2
     if isinstance(value, (list, tuple)):
-        buf = ctypes.create_unicode_buffer('\0'.join(map(type(''), value)) + '\0\0')
+        buf = ctypes.create_unicode_buffer('\0'.join(map(unicode_type, value)) + '\0\0')
         return buf, winreg.REG_MULTI_SZ, len(buf) * 2
     if isinstance(value, numbers.Integral):
         try:
diff --git a/src/duktape/__init__.py b/src/duktape/__init__.py
index fb2e513a32..eef389a0c3 100644
--- a/src/duktape/__init__.py
+++ b/src/duktape/__init__.py
@@ -137,7 +137,7 @@ def writefile(path, data, enc='utf-8'):
     if enc == undefined:
         enc = 'utf-8'
     try:
-        if isinstance(data, type('')):
+        if isinstance(data, unicode_type):
             data = data.encode(enc or 'utf-8')
         atomic_write(path, data)
     except UnicodeEncodeError as e:
@@ -170,8 +170,8 @@ class Function(object):
 
 def to_python(x):
     try:
-        if isinstance(x, (numbers.Number, type(''), bytes, bool)):
-            if isinstance(x, type('')):
+        if isinstance(x, (numbers.Number, unicode_type, bytes, bool)):
+            if isinstance(x, unicode_type):
                 x = x.encode('utf-8')
             if isinstance(x, numbers.Integral):
                 x = int(x)
@@ -195,11 +195,11 @@ class JSError(Exception):
         if isinstance(e, dict):
             if 'message' in e:
                 fn, ln = e.get('fileName'), e.get('lineNumber')
-                msg = type('')(e['message'])
+                msg = unicode_type(e['message'])
                 if ln:
-                    msg = type('')(ln) + ':' + msg
+                    msg = unicode_type(ln) + ':' + msg
                 if fn:
-                    msg = type('')(fn) + ':' + msg
+                    msg = unicode_type(fn) + ':' + msg
                 Exception.__init__(self, msg)
                 for k, v in e.items():
                     if k != 'message':
@@ -207,11 +207,11 @@ class JSError(Exception):
                     else:
                         setattr(self, 'js_message', v)
             else:
-                Exception.__init__(self, type('')(to_python(e)))
+                Exception.__init__(self, unicode_type(to_python(e)))
         else:
             # Happens if js code throws a string or integer rather than a
             # subclass of Error
-            Exception.__init__(self, type('')(e))
+            Exception.__init__(self, unicode_type(e))
             self.name = self.js_message = self.fileName = self.lineNumber = self.stack = None
 
     def as_dict(self):
@@ -246,7 +246,7 @@ def run_in_context(code, ctx, options=None):
     except Exception as e:
         import traceback
         traceback.print_exc()
-        return [False, {'message':type('')(e)}]
+        return [False, {'message':unicode_type(e)}]
     return [True, to_python(ans)]