diff --git a/conftest.py b/conftest.py
index 887aa2833..e85ae6ef1 100644
--- a/conftest.py
+++ b/conftest.py
@@ -9,10 +9,13 @@
 # no fixture-based monkey-patching since star-imports are used for the constants module
 constants.PBKDF2_ITERATIONS = 1
 
+
 # needed to get pretty assertion failures in unit tests:
 if hasattr(pytest, 'register_assert_rewrite'):
     pytest.register_assert_rewrite('borg.testsuite')
 
+
+import borg.cache
 from borg.logger import setup_logging
 
 # Ensure that the loggers exist for all tests
@@ -55,3 +58,22 @@ def pytest_report_header(config, startdir):
     output = "Tests enabled: " + ", ".join(enabled) + "\n"
     output += "Tests disabled: " + ", ".join(disabled)
     return output
+
+
+class DefaultPatches:
+    def __init__(self, request):
+        self.org_cache_wipe_cache = borg.cache.Cache.wipe_cache
+
+        def wipe_should_not_be_called(*a, **kw):
+            raise AssertionError("Cache wipe was triggered, if this is part of the test add @pytest.mark.allow_cache_wipe")
+        if 'allow_cache_wipe' not in request.keywords:
+            borg.cache.Cache.wipe_cache = wipe_should_not_be_called
+        request.addfinalizer(self.undo)
+
+    def undo(self):
+        borg.cache.Cache.wipe_cache = self.org_cache_wipe_cache
+
+
+@pytest.fixture(autouse=True)
+def default_patches(request):
+    return DefaultPatches(request)
diff --git a/src/borg/testsuite/archiver.py b/src/borg/testsuite/archiver.py
index 85f79d712..c41922425 100644
--- a/src/borg/testsuite/archiver.py
+++ b/src/borg/testsuite/archiver.py
@@ -1481,6 +1481,47 @@ def test_unknown_feature_on_mount(self):
         # XXX this might hang if it doesn't raise an error
         self.cmd_raises_unknown_feature(['mount', self.repository_location + '::test', mountpoint])
 
+    @pytest.mark.allow_cache_wipe
+    def test_unknown_mandatory_feature_in_cache(self):
+        if self.prefix:
+            path_prefix = 'ssh://__testsuite__'
+        else:
+            path_prefix = ''
+
+        print(self.cmd('init', '--encryption=repokey', self.repository_location))
+
+        with Repository(self.repository_path, exclusive=True) as repository:
+            if path_prefix:
+                repository._location = Location(self.repository_location)
+            manifest, key = Manifest.load(repository, Manifest.NO_OPERATION_CHECK)
+            with Cache(repository, key, manifest) as cache:
+                cache.begin_txn()
+                cache.cache_config.mandatory_features = set(['unknown-feature'])
+                cache.commit()
+
+        if self.FORK_DEFAULT:
+            self.cmd('create', self.repository_location + '::test', 'input')
+        else:
+            called = False
+            wipe_cache_safe = Cache.wipe_cache
+
+            def wipe_wrapper(*args):
+                nonlocal called
+                called = True
+                wipe_cache_safe(*args)
+
+            with patch.object(Cache, 'wipe_cache', wipe_wrapper):
+                self.cmd('create', self.repository_location + '::test', 'input')
+
+            assert called
+
+        with Repository(self.repository_path, exclusive=True) as repository:
+            if path_prefix:
+                repository._location = Location(self.repository_location)
+            manifest, key = Manifest.load(repository, Manifest.NO_OPERATION_CHECK)
+            with Cache(repository, key, manifest) as cache:
+                assert cache.cache_config.mandatory_features == set([])
+
     def test_progress_on(self):
         self.create_regular_file('file1', size=1024 * 80)
         self.cmd('init', '--encryption=repokey', self.repository_location)