diff --git a/docs/specs/certificate-format.rst b/docs/specs/certificate-format.rst
index 9db67b3..d009985 100644
--- a/docs/specs/certificate-format.rst
+++ b/docs/specs/certificate-format.rst
@@ -1,3 +1,5 @@
+.. _NDN Certificate Format Version 2.0:
+
 NDN Certificate Format Version 2.0
 ==================================