diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index bc171b2..ac667bb 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -204,6 +204,9 @@
   name constraints extension with permitted elements.
 * ``nc_excluded.pem`` - An RSA 2048 bit self-signed certificate containing a
   name constraints extension with excluded elements.
+* ``nc_invalid_ip_netmask.pem`` - An RSA 2048 bit self-signed certificate
+  containing a name constraints extension with a permitted element that has an
+  ``IPv6`` IP and an invalid network mask.
 * ``cp_user_notice_with_notice_reference.pem`` - An RSA 2048 bit self-signed
   certificate containing a certificate policies extension with a
   notice reference in the user notice.