diff --git a/pytest_localserver/http.py b/pytest_localserver/http.py
index 0a14839..df250a3 100644
--- a/pytest_localserver/http.py
+++ b/pytest_localserver/http.py
@@ -25,7 +25,7 @@ def __init__(self, host='127.0.0.1', port=0, application=None, **kwargs):
         self._server = make_server(host, port, self.app, **kwargs)
         self.server_address = self._server.server_address
 
-        super(WSGIServer, self).__init__(
+        super().__init__(
             name=self.__class__,
             target=self._server.serve_forever)
 
@@ -54,7 +54,7 @@ def __bool__(self):
 def _encode_chunk(chunk, charset):
     if isinstance(chunk, str):
         chunk = chunk.encode(charset)
-    return '{0:x}'.format(len(chunk)).encode(charset) + b'\r\n' + chunk + b'\r\n'
+    return '{:x}'.format(len(chunk)).encode(charset) + b'\r\n' + chunk + b'\r\n'
 
 
 class ContentServer(WSGIServer):
@@ -79,7 +79,7 @@ class ContentServer(WSGIServer):
     """
 
     def __init__(self, host='127.0.0.1', port=0, ssl_context=None):
-        super(ContentServer, self).__init__(host, port, self, ssl_context=ssl_context)
+        super().__init__(host, port, self, ssl_context=ssl_context)
         self.content, self.code = ('', 204)  # HTTP 204: No Content
         self.headers = {}
         self.show_post_vars = False
diff --git a/pytest_localserver/https.py b/pytest_localserver/https.py
index 1c2d6b2..a31cee2 100644
--- a/pytest_localserver/https.py
+++ b/pytest_localserver/https.py
@@ -120,7 +120,7 @@ def __init__(self, host='localhost', port=0,
         :param cert: location of file containing server certificate.
         """
 
-        super(SecureContentServer, self).__init__(host, port, ssl_context=(key, cert))
+        super().__init__(host, port, ssl_context=(key, cert))
 
 
 if __name__ == '__main__':  # pragma: no cover
diff --git a/pytest_localserver/plugin.py b/pytest_localserver/plugin.py
index 7686a90..5577d4c 100644
--- a/pytest_localserver/plugin.py
+++ b/pytest_localserver/plugin.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-# -*- coding: utf8 -*-
 #
 # Copyright (C) 2011 Sebastian Rahlf <basti at redtoad dot de>
 #
diff --git a/pytest_localserver/smtp.py b/pytest_localserver/smtp.py
index 3beb9f5..e5a97a9 100644
--- a/pytest_localserver/smtp.py
+++ b/pytest_localserver/smtp.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-# -*- coding: utf8 -*-
 #
 # Copyright (C) 2011 Sebastian Rahlf <basti at redtoad dot de>
 # with some ideas from http://code.activestate.com/recipes/440690/
diff --git a/runtests.py b/runtests.py
index 701574f..c5586a1 100644
--- a/runtests.py
+++ b/runtests.py
@@ -2663,7 +2663,7 @@
 import zlib
 import imp
 
-class DictImporter(object):
+class DictImporter:
     def __init__(self, sources):
         self.sources = sources
 
@@ -2686,7 +2686,7 @@ def load_module(self, fullname):
 
         co = compile(s, fullname, 'exec')
         module = sys.modules.setdefault(fullname, ModuleType(fullname))
-        module.__file__ = "%s/%s" % (__file__, fullname)
+        module.__file__ = "{}/{}".format(__file__, fullname)
         module.__loader__ = self
         if is_pkg:
             module.__path__ = [fullname]
@@ -2701,15 +2701,10 @@ def get_source(self, name):
         return res
 
 if __name__ == "__main__":
-    if sys.version_info >= (3, 0):
-        exec("def do_exec(co, loc): exec(co, loc)\n")
-        import pickle
-        sources = sources.encode("ascii") # ensure bytes
-        sources = pickle.loads(zlib.decompress(base64.decodebytes(sources)))
-    else:
-        import cPickle as pickle
-        exec("def do_exec(co, loc): exec co in loc\n")
-        sources = pickle.loads(zlib.decompress(base64.decodestring(sources)))
+    exec("def do_exec(co, loc): exec(co, loc)\n")
+    import pickle
+    sources = sources.encode("ascii") # ensure bytes
+    sources = pickle.loads(zlib.decompress(base64.decodebytes(sources)))
 
     importer = DictImporter(sources)
     sys.meta_path.insert(0, importer)
diff --git a/tests/test_http.py b/tests/test_http.py
index 4bb1018..f9e1bce 100644
--- a/tests/test_http.py
+++ b/tests/test_http.py
@@ -228,7 +228,7 @@ def _format_chunk(chunk):
     if len(r) <= 40:
         return r
     else:
-        return r[:13] + '...' + r[-14:] + ' (length {0})'.format(len(chunk))
+        return r[:13] + '...' + r[-14:] + ' (length {})'.format(len(chunk))
 
 
 def _compare_chunks(expected, actual):