diff --git a/integration/integration.py b/integration/integration.py
index b268139..ba96c82 100644
--- a/integration/integration.py
+++ b/integration/integration.py
@@ -15,15 +15,15 @@ class integration(Spec):
     def _build(self, folder, opts, target, asserts=None):
         # Dynamic sphinx opt overrides
         pairs = map(lambda x: '='.join(x), (opts or {}).items())
-        flags = map(lambda x: '-D {0}'.format(x), pairs)
+        flags = map(lambda x: '-D {}'.format(x), pairs)
         flagstr = ' '.join(flags)
         # Setup
         os.chdir(os.path.join('integration', '_support'))
         build = os.path.join(folder, '_build')
         try:
             # Build
-            cmd = 'sphinx-build {2} -c . -W {0} {1}'.format(
-                folder, build, flagstr)
+            cmd = 'sphinx-build {} -c . -W {} {}'.format(
+                flagstr, folder, build)
             result = run(cmd, warn=True, hide=True)
             if callable(asserts):
                 asserts(result, build, target)
@@ -36,10 +36,10 @@ class integration(Spec):
 
     def _basic_asserts(self, result, build, target):
         # Check for errors
-        msg = "Build failed w/ stderr: {0}"
+        msg = "Build failed w/ stderr: {}"
         assert result.ok, msg.format(result.stderr)
         # Check for vaguely correct output
-        changelog = os.path.join(build, '{0}.html'.format(target))
+        changelog = os.path.join(build, '{}.html'.format(target))
         with open(changelog) as fd:
             text = fd.read()
             assert "1.0.1" in text
diff --git a/integration/util.py b/integration/util.py
index 8e7728b..46bbf8f 100644
--- a/integration/util.py
+++ b/integration/util.py
@@ -46,7 +46,7 @@ class parse_changelog_(Spec):
         ok_(isinstance(changelog, dict))
         eq_(
             set(changelog.keys()),
-            set(('1.0.0', '1.0.1', '1.0', 'unreleased_1_feature')),
+            {'1.0.0', '1.0.1', '1.0', 'unreleased_1_feature'},
         )
         eq_(len(changelog['1.0.0']), 0)
         eq_(len(changelog['unreleased_1_feature']), 0)
diff --git a/releases/__init__.py b/releases/__init__.py
index 632d70b..fc8763c 100644
--- a/releases/__init__.py
+++ b/releases/__init__.py
@@ -46,7 +46,7 @@ def scan_for_spec(keyword):
     # First, test for intermediate '1.2+' style
     matches = release_line_re.findall(keyword)
     if matches:
-        return Spec(">={0}".format(matches[0]))
+        return Spec(">={}".format(matches[0]))
     # Failing that, see if Spec can make sense of it
     try:
         return Spec(keyword)
@@ -80,7 +80,7 @@ def issues_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
             # TODO: deal with % vs .format()
             ref = config.releases_issue_uri % issue_no
         elif config.releases_github_path:
-            ref = "https://github.com/{0}/issues/{1}".format(
+            ref = "https://github.com/{}/issues/{}".format(
                 config.releases_github_path, issue_no)
         # Only generate a reference/link if we were able to make a URI
         if ref:
@@ -111,7 +111,7 @@ def issues_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
                 if part in ('backported', 'major'):
                     keyword = part
                 else:
-                    err = "Gave unknown keyword {0!r} for issue no. {1}"
+                    err = "Gave unknown keyword {!r} for issue no. {}"
                     raise ValueError(err.format(keyword, issue_no))
         # Create temporary node w/ data & final nodes to publish
         node = Issue(
@@ -138,17 +138,17 @@ def release_nodes(text, slug, date, config):
         # TODO: % vs .format()
         uri = config.releases_release_uri % slug
     elif config.releases_github_path:
-        uri = "https://github.com/{0}/tree/{1}".format(
+        uri = "https://github.com/{}/tree/{}".format(
             config.releases_github_path, slug)
     # Only construct link tag if user actually configured release URIs somehow
     if uri:
-        link = '<a class="reference external" href="{0}">{1}</a>'.format(uri, text)
+        link = '<a class="reference external" href="{}">{}</a>'.format(uri, text)
     else:
         link = text
     datespan = ''
     if date:
-        datespan = ' <span style="font-size: 75%;">{0}</span>'.format(date)
-    header = '<h2 style="margin-bottom: 0.3em;">{0}{1}</h2>'.format(
+        datespan = ' <span style="font-size: 75%;">{}</span>'.format(date)
+    header = '<h2 style="margin-bottom: 0.3em;">{}{}</h2>'.format(
         link, datespan)
     return nodes.section('',
         nodes.raw(rawtext='', text=header, format='html'),
@@ -190,7 +190,7 @@ def generate_unreleased_entry(header, line, issues, manager, app):
         None,
         app.config
     )]
-    log("Creating {0!r} faux-release with {1!r}".format(line, issues))
+    log("Creating {!r} faux-release with {!r}".format(line, issues))
     return {
         'obj': Release(number=line, date=None, nodelist=nodelist),
         'entries': issues,
@@ -207,13 +207,13 @@ def append_unreleased_entries(app, manager, releases):
     """
     for family, lines in six.iteritems(manager):
         for type_ in ('bugfix', 'feature'):
-            bucket = 'unreleased_{0}'.format(type_)
+            bucket = 'unreleased_{}'.format(type_)
             if bucket not in lines: # Implies unstable prehistory + 0.x fam
                 continue
             issues = lines[bucket]
-            fam_prefix = "{0}.x ".format(family) if len(manager) > 1 else ""
-            header = "Next {0}{1} release".format(fam_prefix, type_)
-            line = "unreleased_{0}.x_{1}".format(family, type_)
+            fam_prefix = "{}.x ".format(family) if len(manager) > 1 else ""
+            header = "Next {}{} release".format(fam_prefix, type_)
+            line = "unreleased_{}.x_{}".format(family, type_)
             releases.append(
                 generate_unreleased_entry(header, line, issues, manager, app)
             )
@@ -248,7 +248,7 @@ def construct_entry_with_release(focus, issues, manager, log, releases, rest):
         missing = [i for i in explicit if i not in issues]
         if missing:
             raise ValueError(
-                "Couldn't find issue(s) #{0} in the changelog!".format(
+                "Couldn't find issue(s) #{} in the changelog!".format(
                     ', '.join(missing)))
         # Obtain the explicitly named issues from global list
         entries = []
@@ -359,9 +359,9 @@ def construct_entry_without_release(focus, issues, manager, log, rest):
         buried = focus.traverse(Issue)
         if buried:
             msg = """
-Found issue node ({0!r}) buried inside another node:
+Found issue node ({!r}) buried inside another node:
 
-{1}
+{}
 
 Please double-check your ReST syntax! There is probably text in the above
 output that will show you which part of your changelog to look at.
@@ -629,7 +629,7 @@ def setup(app):
         ('unstable_prehistory', False),
     ):
         app.add_config_value(
-            name='releases_{0}'.format(key), default=default, rebuild='html'
+            name='releases_{}'.format(key), default=default, rebuild='html'
         )
     # Register intermediate roles
     for x in list(ISSUE_TYPES) + ['issue']:
diff --git a/releases/line_manager.py b/releases/line_manager.py
index ef73ecb..002efbf 100644
--- a/releases/line_manager.py
+++ b/releases/line_manager.py
@@ -34,10 +34,7 @@ class LineManager(dict):
         if major_number == 0 and self.config.releases_unstable_prehistory:
             keys = ['unreleased']
         # Either way, the buckets default to an empty list
-        empty = {}
-        for key in keys:
-            empty[key] = []
-        self[major_number] = empty
+        self[major_number] = {key: [] for key in keys}
 
     @property
     def unstable_prehistory(self):
diff --git a/releases/models.py b/releases/models.py
index 89a912c..d980e9c 100644
--- a/releases/models.py
+++ b/releases/models.py
@@ -110,18 +110,18 @@ class Issue(nodes.Element):
         # Make sure truly-default spec skips 0.x if prehistory was unstable.
         stable_families = manager.stable_families
         if manager.config.releases_unstable_prehistory and stable_families:
-            specstr = ">={0}".format(min(stable_families))
+            specstr = ">={}".format(min(stable_families))
         if self.is_featurelike:
             # TODO: if app->config-><releases_always_forwardport_features or
             # w/e
             if True:
-                specstr = ">={0}".format(max(manager.keys()))
+                specstr = ">={}".format(max(manager.keys()))
         else:
             # Can only meaningfully limit to minor release buckets if they
             # actually exist yet.
             buckets = self.minor_releases(manager)
             if buckets:
-                specstr = ">={0}".format(max(buckets))
+                specstr = ">={}".format(max(buckets))
         return Spec(specstr) if specstr else Spec()
 
     def add_to_manager(self, manager):
@@ -178,7 +178,7 @@ class Issue(nodes.Element):
         elif self.spec:
             flag = self.spec
         if flag:
-            flag = ' ({0})'.format(flag)
+            flag = ' ({})'.format(flag)
         return '<{issue.type} #{issue.number}{flag}>'.format(issue=self,
                                                              flag=flag)
 
@@ -200,4 +200,4 @@ class Release(nodes.Element):
         return int(self.number.split('.')[0])
 
     def __repr__(self):
-        return '<release {0}>'.format(self.number)
+        return '<release {}>'.format(self.number)
diff --git a/releases/util.py b/releases/util.py
index 168081a..083b08a 100644
--- a/releases/util.py
+++ b/releases/util.py
@@ -30,8 +30,8 @@ def parse_changelog(path):
     For example, answering the above questions is as simple as::
 
         changelog = parse_changelog("/path/to/changelog")
-        print("Unreleased issues for 2.3.x: {0}".format(changelog['2.3']))
-        print("Contents of v1.2.1: {0}".format(changelog['1.2.1']))
+        print("Unreleased issues for 2.3.x: {}".format(changelog['2.3']))
+        print("Contents of v1.2.1: {}".format(changelog['1.2.1']))
 
     :param str path: A relative or absolute file path string.
 
@@ -75,7 +75,7 @@ def parse_changelog(path):
         # unreleased_N_feature
         unreleased = manager[family].pop('unreleased_feature', None)
         if unreleased is not None:
-            ret['unreleased_{0}_feature'.format(family)] = unreleased
+            ret['unreleased_{}_feature'.format(family)] = unreleased
         # - bring over all per-line buckets from manager (flattening)
         # Here, all that's left in the per-family bucket should be lines, not
         # unreleased_*
@@ -212,7 +212,7 @@ def make_app(**kwargs):
         app.env.temp_data['docname'] = kwargs.pop('docname')
     # Allow config overrides via kwargs
     for name in kwargs:
-        config['releases_{0}'.format(name)] = kwargs[name]
+        config['releases_{}'.format(name)] = kwargs[name]
     # Stitch together as the sphinx app init() usually does w/ real conf files
     app.config._raw_config = config
     # init_values() requires a 'warn' runner on Sphinx 1.3-1.6, so if we seem
@@ -231,7 +231,4 @@ def changelog2dict(changelog):
 
     See `parse_changelog` docstring for return value details.
     """
-    d = {}
-    for r in changelog:
-        d[r['obj'].number] = r['entries']
-    return d
+    return {r['obj'].number: r['entries'] for r in changelog}
diff --git a/tests/_util.py b/tests/_util.py
index bde6257..592036b 100644
--- a/tests/_util.py
+++ b/tests/_util.py
@@ -112,8 +112,8 @@ def expect_releases(entries, release_map, skip_initial=False, app=None):
         kwargs['app'] = app
     changelog = changelog2dict(releases(*entries, **kwargs))
     snapshot = dict(changelog)
-    err = "Got unexpected contents for {0}: wanted {1}, got {2}"
-    err += "\nFull changelog: {3!r}\n"
+    err = "Got unexpected contents for {}: wanted {}, got {}"
+    err += "\nFull changelog: {!r}\n"
     for rel, issues in six.iteritems(release_map):
         found = changelog.pop(rel)
         eq_(set(found), set(issues), err.format(rel, issues, found, snapshot))
@@ -121,4 +121,4 @@ def expect_releases(entries, release_map, skip_initial=False, app=None):
     for key in list(changelog.keys()):
         if not changelog[key]:
             del changelog[key]
-    ok_(not changelog, "Found leftovers: {0}".format(changelog))
+    ok_(not changelog, "Found leftovers: {}".format(changelog))