diff --git a/oauth2client/client.py b/oauth2client/client.py
index 6b580a0..4e8e616 100644
--- a/oauth2client/client.py
+++ b/oauth2client/client.py
@@ -925,7 +925,7 @@
           defaults to Google's endpoints but any OAuth 2.0 provider can be used.
         revoke_uri: string, URI for revoke endpoint.
         kwargs: kwargs, Additional parameters to add to the JWT token, for
-          example prn=joe@xample.org."""
+          example sub=joe@xample.org."""
 
       super(SignedJwtAssertionCredentials, self).__init__(
           None,
diff --git a/tests/test_oauth2client_jwt.py b/tests/test_oauth2client_jwt.py
index 0016153..4af0030 100644
--- a/tests/test_oauth2client_jwt.py
+++ b/tests/test_oauth2client_jwt.py
@@ -217,7 +217,7 @@
         'some_account@example.com',
         private_key,
         scope='read+write',
-        prn='joe@example.org')
+        sub='joe@example.org')
     http = HttpMockSequence([
       ({'status': '200'}, '{"access_token":"1/3w","expires_in":3600}'),
       ({'status': '200'}, 'echo_request_headers'),
@@ -232,7 +232,7 @@
         'some_account@example.com',
         private_key,
         scope='read+write',
-        prn='joe@example.org')
+        sub='joe@example.org')
     json = credentials.to_json()
     restored = Credentials.new_from_json(json)
     self.assertEqual(credentials.private_key, restored.private_key)
@@ -257,7 +257,7 @@
         'some_account@example.com',
         private_key,
         scope='read+write',
-        prn='joe@example.org')
+        sub='joe@example.org')
 
     content = self._credentials_refresh(credentials)
 
@@ -269,7 +269,7 @@
         'some_account@example.com',
         private_key,
         scope='read+write',
-        prn='joe@example.org')
+        sub='joe@example.org')
 
     (filehandle, filename) = tempfile.mkstemp()
     os.close(filehandle)
@@ -305,7 +305,7 @@
         'some_account@example.com',
         private_key,
         scope='read+write',
-        prn='joe@example.org')
+        sub='joe@example.org')
     try:
       credentials._generate_assertion()
       self.fail()