diff --git a/docs/user/advanced.rst b/docs/user/advanced.rst
index 0806ff6d..cd6c4d7d 100644
--- a/docs/user/advanced.rst
+++ b/docs/user/advanced.rst
@@ -225,6 +225,9 @@ Requests can also ignore verifying the SSL certificate if you set ``verify`` to
 
 By default, ``verify`` is set to True. Option ``verify`` only applies to host certs.
 
+Client side certificates
+------------------------
+
 You can also specify a local cert to use as client side certificate, as a single
 file (containing the private key and the certificate) or as a tuple of both
 files' paths::
diff --git a/requests/sessions.py b/requests/sessions.py
index 06e65570..47ad9fae 100644
--- a/requests/sessions.py
+++ b/requests/sessions.py
@@ -343,7 +343,8 @@ class Session(SessionRedirectMixin):
         #: SSL Verification default.
         self.verify = True
 
-        #: SSL client certificate default.
+        #: SSL client certificate default, if String, path to ssl client
+        #: cert file (.pem). If Tuple, ('cert', 'key') pair.
         self.cert = None
 
         #: Maximum number of redirects allowed. If the request exceeds this