add unsupported extension marked critical
diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index 6a7a35e..207515b 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -121,6 +121,9 @@
* ``unsupported_extension.pem`` - An RSA 2048 bit self-signed certificate
containing an unsupported extension type. The OID was encoded as
"1.2.3.4" with an ``extnValue`` of "value".
+* ``unsupported_extension_critical.pem`` - An RSA 2048 bit self-signed
+ certificate containing an unsupported extension type marked critical. The OID
+ was encoded as "1.2.3.4" with an ``extnValue`` of "value".
Custom X.509 Request Vectors
~~~~~~~~~~~~~~~~~~~~~~~~~~~~