diff --git a/tests/test_x509.py b/tests/test_x509.py
index 9567b64..e635805 100644
--- a/tests/test_x509.py
+++ b/tests/test_x509.py
@@ -219,7 +219,9 @@
         assert len(rev0.extensions) == 0
         with pytest.raises(x509.ExtensionNotFound):
             rev0.extensions.get_extension_for_oid(x509.OID_CRL_REASON)
+        with pytest.raises(x509.ExtensionNotFound):
             rev0.extensions.get_extension_for_oid(x509.OID_CERTIFICATE_ISSUER)
+        with pytest.raises(x509.ExtensionNotFound):
             rev0.extensions.get_extension_for_oid(x509.OID_INVALIDITY_DATE)
 
         # Test manual retrieval of extension values.