diff --git a/doc/conf.py b/doc/conf.py
index 37051fac..22c25e43 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -73,7 +73,7 @@
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = "en"
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
diff --git a/fedmsg/tests/crypto/test_utils.py b/fedmsg/tests/crypto/test_utils.py
index 03d5a072..0d418669 100644
--- a/fedmsg/tests/crypto/test_utils.py
+++ b/fedmsg/tests/crypto/test_utils.py
@@ -148,4 +148,4 @@ def test_invalidate_cache(self, mock_load_cert):
             self.assertEqual(('fresh_ca', None), utils._cached_certificates[location])
         self.assertEqual('fresh_ca', ca)
         self.assertTrue(crl is None)
-        mock_load_cert.called_once_with('/crt')
+        mock_load_cert.assert_called_once_with('/crt')
diff --git a/fedmsg/tests/test_commands.py b/fedmsg/tests/test_commands.py
index 758a5497..9d3cca23 100644
--- a/fedmsg/tests/test_commands.py
+++ b/fedmsg/tests/test_commands.py
@@ -135,7 +135,7 @@ def mock_tail(self, topic="", passive=False, **kw):
 
         output = stdout.getvalue()
         expected = "{'topic': 'topic'}\n"
-        assert(output.endswith(expected))
+        assert output.endswith(expected)
 
     @mock.patch("sys.argv", new_callable=lambda: ["fedmsg-tail", "--pretty"])
     @mock.patch("sys.stdout", new_callable=six.StringIO)
@@ -160,7 +160,7 @@ def mock_tail(self, topic="", passive=False, **kw):
 
         output = stdout.getvalue()
         expected = "{'msg': {'hello': 'world'},"
-        assert(expected in output)
+        assert expected in output
 
     @mock.patch("sys.argv", new_callable=lambda: ["fedmsg-tail", "--really-pretty"])
     @mock.patch("sys.stdout", new_callable=six.StringIO)
@@ -186,7 +186,7 @@ def mock_tail(self, topic="", passive=False, **kw):
 
         output = stdout.getvalue()
         expected = '\x1b[33m"hello"\x1b[39;49;00m'
-        assert(expected in output)
+        assert expected in output
 
     @mock.patch("sys.argv", new_callable=lambda: ["fedmsg-config"])
     @mock.patch("sys.stdout", new_callable=six.StringIO)
diff --git a/fedmsg/tests/test_threads.py b/fedmsg/tests/test_threads.py
index aab0015f..4063bcd5 100644
--- a/fedmsg/tests/test_threads.py
+++ b/fedmsg/tests/test_threads.py
@@ -140,7 +140,7 @@ def run(shmelf):
         thread.start()
         thread.join()
 
-        assert(self.test_reinit_success)
+        assert self.test_reinit_success
 
 
 if __name__ == '__main__':