diff --git a/src/allmydata/test/bench_dirnode.py b/src/allmydata/test/bench_dirnode.py
index ffc6637c0..676f00219 100644
--- a/src/allmydata/test/bench_dirnode.py
+++ b/src/allmydata/test/bench_dirnode.py
@@ -24,10 +24,17 @@ class ContainerNode:
         return self._cap.to_string()
     def is_readonly(self):
         return False
-class FakeNodeMaker:
-    def create_from_cap(self, writecap, readcap=None):
+    def is_mutable(self):
+        return True
+
+class FakeNode:
+    def raise_error(self):
         return None
 
+class FakeNodeMaker:
+    def create_from_cap(self, writecap, readcap=None, deep_immutable=False, name=''):
+        return FakeNode()
+
 def random_unicode(l):
     while True:
         try: