diff --git a/src/calibre/utils/__init__.py b/src/calibre/utils/__init__.py
index d019555817..abed0fd8b0 100644
--- a/src/calibre/utils/__init__.py
+++ b/src/calibre/utils/__init__.py
@@ -1,4 +1,7 @@
 #!/usr/bin/env  python2
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net'
 __docformat__ = 'restructuredtext en'
@@ -35,8 +38,8 @@ def unpickle_binary_string(data):
         which = data[offset:offset+1]
         offset += 1
         if which == BINSTRING:
-            sz, = struct.unpack_from(b'<i', data, offset)
-            offset += struct.calcsize(b'<i')
+            sz, = struct.unpack_from('<i', data, offset)
+            offset += struct.calcsize('<i')
         elif which == SHORT_BINSTRING:
             sz = ord(data[offset])
             offset += 1
diff --git a/src/calibre/utils/config_base.py b/src/calibre/utils/config_base.py
index f3a1ddcc06..2a7053717d 100644
--- a/src/calibre/utils/config_base.py
+++ b/src/calibre/utils/config_base.py
@@ -1,7 +1,8 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
 
-from __future__ import print_function
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 __license__   = 'GPL v3'
 __copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
@@ -284,7 +285,7 @@ class OptionSet(object):
         try:
             if not isinstance(src, unicode_type):
                 src = src.decode('utf-8')
-            src = src.replace(u'PyQt%d.QtCore' % 4, u'PyQt5.QtCore')
+            src = src.replace('PyQt%d.QtCore' % 4, 'PyQt5.QtCore')
             exec(src, options)
         except Exception as err:
             try:
@@ -360,7 +361,7 @@ class Config(ConfigInterface):
         return os.path.join(config_dir, self.filename_base + '.py.json')
 
     def parse(self):
-        src = u''
+        src = ''
         migrate = False
         path = self.config_file_path
         if os.path.exists(path):
@@ -554,7 +555,7 @@ if prefs['installation_uuid'] is None:
 
 
 def tweaks_file():
-    return os.path.join(config_dir, u'tweaks.json')
+    return os.path.join(config_dir, 'tweaks.json')
 
 
 def make_unicode(obj):
@@ -623,7 +624,7 @@ def read_custom_tweaks():
             import traceback
             traceback.print_exc()
             return ans
-    old_tweaks_file = tf.rpartition(u'.')[0] + u'.py'
+    old_tweaks_file = tf.rpartition('.')[0] + '.py'
     if os.path.exists(old_tweaks_file):
         ans = exec_tweaks(old_tweaks_file)
         ans = make_unicode(ans)
diff --git a/src/calibre/utils/date.py b/src/calibre/utils/date.py
index 1e07598dd1..9845641062 100644
--- a/src/calibre/utils/date.py
+++ b/src/calibre/utils/date.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python2
 # vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
-from __future__ import with_statement
+from __future__ import absolute_import, division, print_function, unicode_literals
 
 __license__   = 'GPL v3'
 __copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
@@ -34,7 +34,7 @@ if iswindows:
 elif isosx:
     try:
         date_fmt = plugins['usbobserver'][0].date_format()
-        parse_date_day_first = date_fmt.index(u'd') < date_fmt.index(u'M')
+        parse_date_day_first = date_fmt.index('d') < date_fmt.index('M')
     except:
         parse_date_day_first = False
 else:
@@ -42,7 +42,7 @@ else:
         def first_index(raw, queries):
             for q in queries:
                 try:
-                    return raw.index(q)
+                    return raw.index(native_string_type(q))
                 except ValueError:
                     pass
             return -1
@@ -445,31 +445,31 @@ def clean_date_for_sort(dt, fmt=None):
 def replace_months(datestr, clang):
     # Replace months by english equivalent for parse_date
     frtoen = {
-        u'[jJ]anvier': u'jan',
-        u'[fF].vrier': u'feb',
-        u'[mM]ars': u'mar',
-        u'[aA]vril': u'apr',
-        u'[mM]ai': u'may',
-        u'[jJ]uin': u'jun',
-        u'[jJ]uillet': u'jul',
-        u'[aA]o.t': u'aug',
-        u'[sS]eptembre': u'sep',
-        u'[Oo]ctobre': u'oct',
-        u'[nN]ovembre': u'nov',
-        u'[dD].cembre': u'dec'}
+        '[jJ]anvier': 'jan',
+        '[fF].vrier': 'feb',
+        '[mM]ars': 'mar',
+        '[aA]vril': 'apr',
+        '[mM]ai': 'may',
+        '[jJ]uin': 'jun',
+        '[jJ]uillet': 'jul',
+        '[aA]o.t': 'aug',
+        '[sS]eptembre': 'sep',
+        '[Oo]ctobre': 'oct',
+        '[nN]ovembre': 'nov',
+        '[dD].cembre': 'dec'}
     detoen = {
-        u'[jJ]anuar': u'jan',
-        u'[fF]ebruar': u'feb',
-        u'[mM].rz': u'mar',
-        u'[aA]pril': u'apr',
-        u'[mM]ai': u'may',
-        u'[jJ]uni': u'jun',
-        u'[jJ]uli': u'jul',
-        u'[aA]ugust': u'aug',
-        u'[sS]eptember': u'sep',
-        u'[Oo]ktober': u'oct',
-        u'[nN]ovember': u'nov',
-        u'[dD]ezember': u'dec'}
+        '[jJ]anuar': 'jan',
+        '[fF]ebruar': 'feb',
+        '[mM].rz': 'mar',
+        '[aA]pril': 'apr',
+        '[mM]ai': 'may',
+        '[jJ]uni': 'jun',
+        '[jJ]uli': 'jul',
+        '[aA]ugust': 'aug',
+        '[sS]eptember': 'sep',
+        '[Oo]ktober': 'oct',
+        '[nN]ovember': 'nov',
+        '[dD]ezember': 'dec'}
 
     if clang == 'fr':
         dictoen = frtoen
diff --git a/src/calibre/utils/linux_trash.py b/src/calibre/utils/linux_trash.py
index 715f2bad4b..2de771224d 100644
--- a/src/calibre/utils/linux_trash.py
+++ b/src/calibre/utils/linux_trash.py
@@ -119,7 +119,7 @@ def find_ext_volume_global_trash(volume_root):
     if not op.isdir(trash_dir) or op.islink(trash_dir) or not (mode & stat.S_ISVTX):
         return None
 
-    trash_dir = op.join(trash_dir, str(uid))
+    trash_dir = op.join(trash_dir, unicode_type(uid))
     try:
         check_create(trash_dir)
     except OSError:
diff --git a/src/calibre/utils/test_lock.py b/src/calibre/utils/test_lock.py
index ebdc853b60..f475b0b15b 100644
--- a/src/calibre/utils/test_lock.py
+++ b/src/calibre/utils/test_lock.py
@@ -19,7 +19,7 @@ from calibre.utils.tdir_in_cache import (
     clean_tdirs_in, is_tdir_locked, retry_lock_tdir, tdir_in_cache, tdirs_in,
     unlock_file
 )
-from polyglot.builtins import iteritems, getcwd
+from polyglot.builtins import iteritems, getcwd, native_string_type
 
 
 def FastFailEF(name):
@@ -53,7 +53,7 @@ def run_worker(mod, func, **kw):
     if iswindows:
         import win32process
         kw['creationflags'] = win32process.CREATE_NO_WINDOW
-    kw['env'] = {str(k): str(v)
+    kw['env'] = {native_string_type(k): native_string_type(v)
                  for k, v in iteritems(env)}  # windows needs bytes in env
     return subprocess.Popen(exe, **kw)