diff --git a/mitogen/core.py b/mitogen/core.py
index d829d624..9aa95973 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -374,7 +374,7 @@ def io_op(func, *args):
 
     :returns:
         Tuple of `(return_value, disconnected)`, where `return_value` is the
-        return value of `func(\*args)`, and `disconnected` is :data:`True` if
+        return value of `func(*args)`, and `disconnected` is :data:`True` if
         disconnection was detected, otherwise :data:`False`.
     """
     while True:
diff --git a/mitogen/parent.py b/mitogen/parent.py
index a4e17b93..45c8e2f2 100644
--- a/mitogen/parent.py
+++ b/mitogen/parent.py
@@ -1280,7 +1280,7 @@ class CallChain(object):
 
     def call_async(self, fn, *args, **kwargs):
         """
-        Arrange for `fn(\*args, \**kwargs)` to be invoked on the context's main
+        Arrange for `fn(*args, **kwargs)` to be invoked on the context's main
         thread.
 
         :param fn:
diff --git a/mitogen/ssh.py b/mitogen/ssh.py
index f8255865..ee97425b 100644
--- a/mitogen/ssh.py
+++ b/mitogen/ssh.py
@@ -291,8 +291,8 @@ class Stream(mitogen.parent.Stream):
                 raise HostKeyError(self.hostkey_failed_msg)
             elif buf.lower().startswith((
                     PERMDENIED_PROMPT,
-                    b("%s@%s: %s" % (self.username, self.hostname,
-                                     PERMDENIED_PROMPT)),
+                    b("%s@%s: " % (self.username, self.hostname))
+                        + PERMDENIED_PROMPT,
                 )):
                 # issue #271: work around conflict with user shell reporting
                 # 'permission denied' e.g. during chdir($HOME) by only matching
diff --git a/tox.ini b/tox.ini
index ae761121..6bf8bb53 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,6 +2,8 @@
 envlist =
     py26,
     py27,
+    py35,
+    py36,
 
 [testenv]
 deps =