diff --git a/bundles/routing/dynamic.rst b/bundles/routing/dynamic.rst
index 1ff96349..cae21082 100644
--- a/bundles/routing/dynamic.rst
+++ b/bundles/routing/dynamic.rst
@@ -278,6 +278,11 @@ Of course you can also have several parameters, as with normal Symfony
 routes. The semantics and rules for patterns, defaults and requirements are
 exactly the same as in core routes.
 
+.. note::
+
+    The ``RouteDefaultsValidator`` validates the route defaults parameters.
+    For more information, see :ref:`bundle-routing-route-defaults-validator`.
+
 Your controller can expect the ``$id`` parameter as well as the ``$contentDocument``
 as you set a content on the route. The content could be used to define an intro
 section that is the same for each project or other shared data. If you don't
diff --git a/bundles/routing/dynamic_customize.rst b/bundles/routing/dynamic_customize.rst
index 23084fd2..933f2e4a 100644
--- a/bundles/routing/dynamic_customize.rst
+++ b/bundles/routing/dynamic_customize.rst
@@ -156,3 +156,16 @@ information on creating custom services.
 
 .. _`Creating and configuring services in the container`: http://symfony.com/doc/current/book/service_container.html#creating-configuring-services-in-the-container/
 .. _`PHPCR-ODM`: http://www.doctrine-project.org/projects/phpcr-odm.html
+
+.. _bundle-routing-route-defaults-validator:
+
+The RouteDefaultsValidator
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The route ``getDefaults`` method has a ``RouteDefaults`` constraint.
+When a route is validated, the ``RouteDefaultsValidator`` will be called.
+If the ``_controller`` or the ``_template`` defaults are set, the validator
+will check that they exist.
+
+You can override the validator by setting the
+``cmf_routing.validator.route_defaults.class`` parameter.