diff --git a/README.rst b/README.rst
index b65230dc4..fac36dbd7 100644
--- a/README.rst
+++ b/README.rst
@@ -91,4 +91,4 @@ email to client-dev+subscribe@letsencrypt.org)
 
 .. _Freenode: https://freenode.net
 .. _client-dev: https://groups.google.com/a/letsencrypt.org/forum/#!forum/client-dev
-.. _CONTRIBUTING.rst: https://github.com/letsencrypt/lets-encrypt-preview/blob/master/CONTRIBUTING.rst
+.. _CONTRIBUTING.md: https://github.com/letsencrypt/lets-encrypt-preview/blob/master/CONTRIBUTING.md