diff --git a/flask/templating.py b/flask/templating.py
index c809a63f..e5d896cb 100644
--- a/flask/templating.py
+++ b/flask/templating.py
@@ -129,8 +129,8 @@ def render_template_string(source, **context):
     """Renders a template from the given template source string
     with the given context.
 
-    :param template_name: the sourcecode of the template to be
-                          rendered
+    :param source: the sourcecode of the template to be
+                   rendered
     :param context: the variables that should be available in the
                     context of the template.
     """