diff --git a/setup/__init__.py b/setup/__init__.py
index 780c53d7cf..7d4c49734d 100644
--- a/setup/__init__.py
+++ b/setup/__init__.py
@@ -27,6 +27,7 @@ __version__ = __appname__ = modules = functions = basenames = scripts = None
 
 _cache_dir_built = False
 
+
 def newer(targets, sources):
     if isinstance(targets, basestring):
         targets = [targets]
@@ -40,6 +41,14 @@ def newer(targets, sources):
     newest_source, oldest_target = max(stimes), min(ttimes)
     return newest_source > oldest_target
 
+
+def download_securely(url):
+    # We use curl here as on some OSes (OS X) when bootstrapping calibre,
+    # python will be unable to validate certificates until after cacerts is
+    # installed
+    return subprocess.check_output(['curl', '-fsSL', url])
+
+
 def build_cache_dir():
     global _cache_dir_built
     ans = os.path.join(os.path.dirname(SRC), '.build-cache')
@@ -52,11 +61,13 @@ def build_cache_dir():
                 raise
     return ans
 
+
 def require_git_master():
     if subprocess.check_output(['git', 'symbolic-ref', '--short', 'HEAD']).strip() != 'master':
         print >>sys.stderr, 'You must be in the master git branch'
         raise SystemExit(1)
 
+
 def require_clean_git():
     c = subprocess.check_call
     p = subprocess.Popen
@@ -70,6 +81,7 @@ def require_clean_git():
             print >>sys.stderr, 'Your git index contains uncommitted changes'
             raise SystemExit(1)
 
+
 def initialize_constants():
     global __version__, __appname__, modules, functions, basenames, scripts
 
@@ -102,10 +114,12 @@ def initialize_constants():
         modules[x] = list(map(e2m, entry_points[y]))
         scripts[x] = list(map(e2s, entry_points[y]))
 
+
 initialize_constants()
 
 preferred_encoding = 'utf-8'
 
+
 def prints(*args, **kwargs):
     '''
     Print unicode arguments safely by encoding them to preferred_encoding
@@ -144,11 +158,14 @@ def prints(*args, **kwargs):
             file.write(sep)
     file.write(end)
 
+
 warnings = []
 
+
 def get_warnings():
     return list(warnings)
 
+
 class Command(object):
 
     SRC = SRC
@@ -252,6 +269,7 @@ class Command(object):
         warnings.append((args, kwargs))
         sys.stdout.flush()
 
+
 def installer_name(ext, is64bit=False):
     if is64bit and ext == 'msi':
         return 'dist/%s-64bit-%s.msi'%(__appname__, __version__)
@@ -266,6 +284,3 @@ def installer_name(ext, is64bit=False):
     if is64bit:
         ans = ans.replace('i686', 'x86_64')
     return ans
-
-
-
diff --git a/setup/mathjax.py b/setup/mathjax.py
index 4776120c63..991461c8c5 100644
--- a/setup/mathjax.py
+++ b/setup/mathjax.py
@@ -8,14 +8,15 @@ __copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
 import os, shutil
-from urllib import urlretrieve
+from io import BytesIO
 from zipfile import ZipFile, ZIP_STORED, ZipInfo
 from hashlib import sha1
 from tempfile import mkdtemp, SpooledTemporaryFile
 is_ci = os.environ.get('CI', '').lower() == 'true'
 
 
-from setup import Command
+from setup import Command, download_securely
+
 
 class MathJax(Command):
 
@@ -29,8 +30,8 @@ class MathJax(Command):
 
     def download_mathjax_release(self, tdir, url):
         self.info('Downloading MathJax:', url)
-        filename = urlretrieve(url)[0]
-        with ZipFile(filename) as zf:
+        raw = download_securely(url)
+        with ZipFile(BytesIO(raw)) as zf:
             zf.extractall(tdir)
             return os.path.join(tdir, 'MathJax-master')
 
diff --git a/setup/resources.py b/setup/resources.py
index 6a0d122ee7..d3c9614c6f 100644
--- a/setup/resources.py
+++ b/setup/resources.py
@@ -6,12 +6,13 @@ __license__   = 'GPL v3'
 __copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-import os, cPickle, re, shutil, marshal, zipfile, glob, time, sys, hashlib, json, errno, subprocess
+import os, cPickle, re, shutil, marshal, zipfile, glob, time, sys, hashlib, json, errno
 from zlib import compress
 from itertools import chain
 is_ci = os.environ.get('CI', '').lower() == 'true'
 
-from setup import Command, basenames, __appname__
+from setup import Command, basenames, __appname__, download_securely
+
 
 def get_opts_from_parser(parser):
     def do_opt(opt):
@@ -27,11 +28,6 @@ def get_opts_from_parser(parser):
             for x in do_opt(o):
                 yield x
 
-def download_securely(url):
-    # We use curl here as on some OSes (OS X) when bootstrapping calibre,
-    # python will be unable to validate certificates until after cacerts is
-    # installed
-    return subprocess.check_output(['curl', '-fsSL', url])
 
 class Coffee(Command):  # {{{
 
@@ -128,6 +124,7 @@ class Coffee(Command):  # {{{
             os.remove(x)
 # }}}
 
+
 class Kakasi(Command):  # {{{
 
     description = 'Compile resources for unihandecode'
@@ -229,6 +226,7 @@ class Kakasi(Command):  # {{{
             shutil.rmtree(kakasi)
 # }}}
 
+
 class CACerts(Command):  # {{{
 
     description = 'Get updated mozilla CA certificate bundle'
@@ -256,6 +254,7 @@ class CACerts(Command):  # {{{
         get_https_resource_securely('https://calibre-ebook.com', cacerts=self.b(self.CA_PATH))
 # }}}
 
+
 class RecentUAs(Command):
 
     description = 'Get updated list of recent browser user agents'
@@ -291,6 +290,7 @@ class RecentUAs(Command):
         with open(self.UA_PATH, 'wb') as f:
             f.write('\n'.join(lines).encode('ascii'))
 
+
 class RapydScript(Command):  # {{{
 
     description = 'Compile RapydScript to JavaScript'
@@ -300,6 +300,7 @@ class RapydScript(Command):  # {{{
         compile_srv()
 # }}}
 
+
 class Resources(Command):  # {{{
 
     description = 'Compile various needed calibre resources'