diff --git a/.travis.yml b/.travis.yml
index 9cf89caa6..f693fffe7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,6 +21,7 @@ env:
   - TMUX_VERSION=1.9a
 matrix:
   allow_failures:
+  - python: pypy3.3-5.2-alpha1
   - env: TMUX_VERSION=master
 before_install:
   - export PIP_USE_MIRRORS=true
diff --git a/libtmux/session.py b/libtmux/session.py
index 5e141cf8f..ed5aab597 100644
--- a/libtmux/session.py
+++ b/libtmux/session.py
@@ -11,6 +11,7 @@
 import os
 
 from . import exc, formats
+from ._compat import text_type
 from .common import EnvironmentMixin, TmuxMappingObject, \
     TmuxRelationalObject, session_check_name, handle_option_error
 from .window import Window
@@ -72,8 +73,13 @@ def cmd(self, *args, **kwargs):
             Renamed from ``.tmux`` to ``.cmd``.
 
         """
-        if '-t' not in kwargs:
-            kwargs['-t'] = self.id
+        # if -t is not set in any arg yet
+        if not any('-t' in text_type(x) for x in args):
+            # insert -t immediately after 1st arg, as per tmux format
+            new_args = [args[0]]
+            new_args += ['-t', self.id]
+            new_args += args[1:]
+            args = new_args
         return self.server.cmd(*args, **kwargs)
 
     def attach_session(self):
diff --git a/tests/test_session.py b/tests/test_session.py
index 96460d1fa..c1e8dfcfb 100644
--- a/tests/test_session.py
+++ b/tests/test_session.py
@@ -235,3 +235,12 @@ def test_periods_raise_badsessionname(server, session, session_name, raises):
         session.rename_session(new_name)
         with pytest.raises(exc.LibTmuxException):
             server.switch_client(new_name)
+
+
+def test_cmd_inserts_sesion_id(session):
+    current_session_id = session.id
+    last_arg = 'last-arg'
+    cmd = session.cmd('not-a-command', last_arg)
+    assert '-t' in cmd.cmd
+    assert current_session_id in cmd.cmd
+    assert cmd.cmd[-1] == last_arg