diff --git a/tests/test_x509_ext.py b/tests/test_x509_ext.py
index 8cbce10..565cf57 100644
--- a/tests/test_x509_ext.py
+++ b/tests/test_x509_ext.py
@@ -1858,6 +1858,10 @@
                 AuthorityInformationAccessOID.CA_ISSUERS, "invalid"
             )
 
+    def test_valid_nonstandard_method (self):
+        ad = x509.AccessDescription("2.999.1", x509.UniformResourceIdentifier(u"http://example.com"))
+        assert ad is not None
+
     def test_repr(self):
         ad = x509.AccessDescription(
             AuthorityInformationAccessOID.OCSP,