diff --git a/src/ZEO/asyncio/marshal.py b/src/ZEO/asyncio/marshal.py
index a4dd81dca..534f8feae 100644
--- a/src/ZEO/asyncio/marshal.py
+++ b/src/ZEO/asyncio/marshal.py
@@ -126,7 +126,10 @@ def reduce_exception(exc):
 
 exception_type_type = type(Exception)
 
-_SAFE_MODULE_NAMES = ('ZopeUndo.Prefix', 'copy_reg', '__builtin__', 'zodbpickle')
+_SAFE_MODULE_NAMES = (
+    'ZopeUndo.Prefix', 'zodbpickle',
+    'builtins', 'copy_reg', '__builtin__',
+)
 
 def find_global(module, name):
     """Helper for message unpickler"""
diff --git a/src/ZEO/tests/ZEO4/zrpc/marshal.py b/src/ZEO/tests/ZEO4/zrpc/marshal.py
index 11b388545..c28287724 100644
--- a/src/ZEO/tests/ZEO4/zrpc/marshal.py
+++ b/src/ZEO/tests/ZEO4/zrpc/marshal.py
@@ -97,7 +97,10 @@ def server_decode(msg):
 
 exception_type_type = type(Exception)
 
-_SAFE_MODULE_NAMES = ('ZopeUndo.Prefix', 'copy_reg', '__builtin__', 'zodbpickle')
+_SAFE_MODULE_NAMES = (
+    'ZopeUndo.Prefix', 'zodbpickle',
+    'builtins', 'copy_reg', '__builtin__',
+)
 
 def find_global(module, name):
     """Helper for message unpickler"""
diff --git a/src/ZEO/tests/testZEO.py b/src/ZEO/tests/testZEO.py
index 51525d317..614e089d6 100644
--- a/src/ZEO/tests/testZEO.py
+++ b/src/ZEO/tests/testZEO.py
@@ -489,6 +489,8 @@ def getConfig(self):
 
 class FileStorageClientHexTests(FileStorageHexTests):
 
+    use_extension_bytes = True
+
     def getConfig(self):
         return """\
         %import ZODB.tests