diff --git a/certbot-apache/tests/autohsts_test.py b/certbot-apache/tests/autohsts_test.py
index 8414f059b..d50fd7ecc 100644
--- a/certbot-apache/tests/autohsts_test.py
+++ b/certbot-apache/tests/autohsts_test.py
@@ -42,8 +42,11 @@ class AutoHSTSTest(util.ApacheTest):
     @mock.patch("certbot_apache._internal.configurator.ApacheConfigurator.restart")
     @mock.patch("certbot_apache._internal.configurator.ApacheConfigurator.enable_mod")
     def test_autohsts_enable_headers_mod(self, mock_enable, _restart):
-        self.config.parser.modules.discard("headers_module")
-        self.config.parser.modules.discard("mod_header.c")
+        try:
+            del self.config.parser.modules["headers_module"]
+            del self.config.parser.modules["mod_header.c"]
+        except KeyError:
+            pass
         self.config.enable_autohsts(mock.MagicMock(), ["ocspvhost.com"])
         self.assertTrue(mock_enable.called)