diff --git a/docs/asgi.rst b/docs/asgi.rst
index 61c0cfa..ec965fd 100644
--- a/docs/asgi.rst
+++ b/docs/asgi.rst
@@ -286,7 +286,8 @@ A *channel layer* should provide an object with these attributes
 
 * ``extensions``, a list of unicode string names indicating which
   extensions this layer provides, or empty if it supports none.
-  The only valid extension names are ``groups``, ``flush`` and ``statistics``.
+  The names defined in this document are ``groups``, ``flush`` and
+  ``statistics``.
 
 A channel layer implementing the ``groups`` extension must also provide: