diff --git a/test/DebugProtoTest.thrift b/test/DebugProtoTest.thrift
index e7119c4..9726d00 100644
--- a/test/DebugProtoTest.thrift
+++ b/test/DebugProtoTest.thrift
@@ -62,7 +62,7 @@
 
 struct HolyMoley {
   1: list<OneOfEach> big,
-  2: set<list<string>> contain,
+  2: set<list<string> (python.immutable = "")> contain,
   3: map<string,list<Bonk>> bonks,
 }
 
@@ -259,10 +259,10 @@
 // The only purpose of this thing is to increase the size of the generated code
 // so that ZlibTest has more highly compressible data to play with.
 struct BlowUp {
-  1: map<list<i32>,set<map<i32,string>>> b1;
-  2: map<list<i32>,set<map<i32,string>>> b2;
-  3: map<list<i32>,set<map<i32,string>>> b3;
-  4: map<list<i32>,set<map<i32,string>>> b4;
+  1: map<list<i32>(python.immutable = ""),set<map<i32,string> (python.immutable = "")>> b1;
+  2: map<list<i32>(python.immutable = ""),set<map<i32,string> (python.immutable = "")>> b2;
+  3: map<list<i32>(python.immutable = ""),set<map<i32,string> (python.immutable = "")>> b3;
+  4: map<list<i32>(python.immutable = ""),set<map<i32,string> (python.immutable = "")>> b4;
 }
 
 
diff --git a/test/FastbinaryTest.py b/test/FastbinaryTest.py
deleted file mode 100755
index 7f6efae..0000000
--- a/test/FastbinaryTest.py
+++ /dev/null
@@ -1,222 +0,0 @@
-#!/usr/bin/env python
-
-#
-# Licensed to the Apache Software Foundation (ASF) under one
-# or more contributor license agreements. See the NOTICE file
-# distributed with this work for additional information
-# regarding copyright ownership. The ASF licenses this file
-# to you under the Apache License, Version 2.0 (the
-# "License"); you may not use this file except in compliance
-# with the License. You may obtain a copy of the License at
-#
-#   http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing,
-# software distributed under the License is distributed on an
-# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-# KIND, either express or implied. See the License for the
-# specific language governing permissions and limitations
-# under the License.
-#
-
-r"""
-thrift --gen py DebugProtoTest.thrift
-./FastbinaryTest.py
-"""
-
-# TODO(dreiss): Test error cases.  Check for memory leaks.
-
-import sys
-sys.path.append('./gen-py')
-
-import math
-from DebugProtoTest import Srv
-from DebugProtoTest.ttypes import *
-from thrift.transport import TTransport
-from thrift.protocol import TBinaryProtocol
-
-import timeit
-from cStringIO import StringIO
-from copy import deepcopy
-from pprint import pprint
-
-class TDevNullTransport(TTransport.TTransportBase):
-  def __init__(self):
-    pass
-  def isOpen(self):
-    return True
-
-ooe1 = OneOfEach()
-ooe1.im_true   = True;
-ooe1.im_false  = False;
-ooe1.a_bite    = 0xd6;
-ooe1.integer16 = 27000;
-ooe1.integer32 = 1<<24;
-ooe1.integer64 = 6000 * 1000 * 1000;
-ooe1.double_precision = math.pi;
-ooe1.some_characters  = "Debug THIS!";
-ooe1.zomg_unicode     = "\xd7\n\a\t";
-
-ooe2 = OneOfEach();
-ooe2.integer16 = 16;
-ooe2.integer32 = 32;
-ooe2.integer64 = 64;
-ooe2.double_precision = (math.sqrt(5)+1)/2;
-ooe2.some_characters  = ":R (me going \"rrrr\")";
-ooe2.zomg_unicode     = "\xd3\x80\xe2\x85\xae\xce\x9d\x20"\
-                        "\xd0\x9d\xce\xbf\xe2\x85\xbf\xd0\xbe"\
-                        "\xc9\xa1\xd0\xb3\xd0\xb0\xcf\x81\xe2\x84\x8e"\
-                        "\x20\xce\x91\x74\x74\xce\xb1\xe2\x85\xbd\xce\xba"\
-                        "\xc7\x83\xe2\x80\xbc";
-
-hm = HolyMoley({"big":[], "contain":set(), "bonks":{}})
-hm.big.append(ooe1)
-hm.big.append(ooe2)
-hm.big[0].a_bite = 0x22;
-hm.big[1].a_bite = 0x22;
-
-hm.contain.add(("and a one", "and a two"))
-hm.contain.add(("then a one, two", "three!", "FOUR!"))
-hm.contain.add(())
-
-hm.bonks["nothing"] = [];
-hm.bonks["something"] = [
-  Bonk({"type":1, "message":"Wait."}),
-  Bonk({"type":2, "message":"What?"}),
-]
-hm.bonks["poe"] = [
-  Bonk({"type":3, "message":"quoth"}),
-  Bonk({"type":4, "message":"the raven"}),
-  Bonk({"type":5, "message":"nevermore"}),
-]
-
-rs = RandomStuff()
-rs.a = 1
-rs.b = 2
-rs.c = 3
-rs.myintlist = range(20)
-rs.maps = {1:Wrapper({"foo":Empty()}),2:Wrapper({"foo":Empty()})}
-rs.bigint = 124523452435L
-rs.triple = 3.14
-
-# make sure this splits two buffers in a buffered protocol
-rshuge = RandomStuff()
-rshuge.myintlist=range(10000)
-
-my_zero = Srv.Janky_result({"arg":5})
-
-def checkWrite(o):
-  trans_fast = TTransport.TMemoryBuffer()
-  trans_slow = TTransport.TMemoryBuffer()
-  prot_fast = TBinaryProtocol.TBinaryProtocolAccelerated(trans_fast)
-  prot_slow = TBinaryProtocol.TBinaryProtocol(trans_slow)
-
-  o.write(prot_fast)
-  o.write(prot_slow)
-  ORIG = trans_slow.getvalue()
-  MINE = trans_fast.getvalue()
-  if ORIG != MINE:
-    print "mine: %s\norig: %s" % (repr(MINE), repr(ORIG))
-
-def checkRead(o):
-  prot = TBinaryProtocol.TBinaryProtocol(TTransport.TMemoryBuffer())
-  o.write(prot)
-
-  slow_version_binary = prot.trans.getvalue()
-
-  prot = TBinaryProtocol.TBinaryProtocolAccelerated(
-           TTransport.TMemoryBuffer(slow_version_binary))
-  c = o.__class__()
-  c.read(prot)
-  if c != o:
-    print "copy: "
-    pprint(eval(repr(c)))
-    print "orig: "
-    pprint(eval(repr(o)))
-
-  prot = TBinaryProtocol.TBinaryProtocolAccelerated(
-           TTransport.TBufferedTransport(
-             TTransport.TMemoryBuffer(slow_version_binary)))
-  c = o.__class__()
-  c.read(prot)
-  if c != o:
-    print "copy: "
-    pprint(eval(repr(c)))
-    print "orig: "
-    pprint(eval(repr(o)))
-
-
-def doTest():
-  checkWrite(hm)
-  no_set = deepcopy(hm)
-  no_set.contain = set()
-  checkRead(no_set)
-  checkWrite(rs)
-  checkRead(rs)
-  checkWrite(rshuge)
-  checkRead(rshuge)
-  checkWrite(my_zero)
-  checkRead(my_zero)
-  checkRead(Backwards({"first_tag2":4, "second_tag1":2}))
-
-  # One case where the serialized form changes, but only superficially.
-  o = Backwards({"first_tag2":4, "second_tag1":2})
-  trans_fast = TTransport.TMemoryBuffer()
-  trans_slow = TTransport.TMemoryBuffer()
-  prot_fast = TBinaryProtocol.TBinaryProtocolAccelerated(trans_fast)
-  prot_slow = TBinaryProtocol.TBinaryProtocol(trans_slow)
-
-  o.write(prot_fast)
-  o.write(prot_slow)
-  ORIG = trans_slow.getvalue()
-  MINE = trans_fast.getvalue()
-  if ORIG == MINE:
-    print "That shouldn't happen."
-
-
-  prot = TBinaryProtocol.TBinaryProtocolAccelerated(TTransport.TMemoryBuffer())
-  o.write(prot)
-  prot = TBinaryProtocol.TBinaryProtocol(
-           TTransport.TMemoryBuffer(
-             prot.trans.getvalue()))
-  c = o.__class__()
-  c.read(prot)
-  if c != o:
-    print "copy: "
-    pprint(eval(repr(c)))
-    print "orig: "
-    pprint(eval(repr(o)))
-
-
-
-def doBenchmark():
-
-  iters = 25000
-
-  setup = """
-from __main__ import hm, rs, TDevNullTransport
-from thrift.protocol import TBinaryProtocol
-trans = TDevNullTransport()
-prot = TBinaryProtocol.TBinaryProtocol%s(trans)
-"""
-
-  setup_fast = setup % "Accelerated"
-  setup_slow = setup % ""
-
-  print "Starting Benchmarks"
-
-  print "HolyMoley Standard = %f" % \
-      timeit.Timer('hm.write(prot)', setup_slow).timeit(number=iters)
-  print "HolyMoley Acceler. = %f" % \
-      timeit.Timer('hm.write(prot)', setup_fast).timeit(number=iters)
-
-  print "FastStruct Standard = %f" % \
-      timeit.Timer('rs.write(prot)', setup_slow).timeit(number=iters)
-  print "FastStruct Acceler. = %f" % \
-      timeit.Timer('rs.write(prot)', setup_fast).timeit(number=iters)
-
-
-
-doTest()
-doBenchmark()
-
diff --git a/test/Makefile.am b/test/Makefile.am
index 593b1c4..c1fd589 100755
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -124,7 +124,6 @@
 	tests.json \
 	ThriftTest.thrift \
 	TypedefTest.thrift \
-	FastbinaryTest.py \
 	result.html \
 	README.md \
 	valgrind.suppress
diff --git a/test/py/FastbinaryTest.py b/test/py/FastbinaryTest.py
new file mode 100755
index 0000000..0583373
--- /dev/null
+++ b/test/py/FastbinaryTest.py
@@ -0,0 +1,215 @@
+#!/usr/bin/env python
+
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+r"""
+PYTHONPATH=./gen-py:../../lib/py/build/lib... ./FastbinaryTest.py
+"""
+
+# TODO(dreiss): Test error cases.  Check for memory leaks.
+
+import math
+import timeit
+
+from copy import deepcopy
+from pprint import pprint
+
+from thrift.transport import TTransport
+from thrift.protocol import TBinaryProtocol
+
+from DebugProtoTest import Srv
+from DebugProtoTest.ttypes import Backwards, Bonk, Empty, HolyMoley, OneOfEach, RandomStuff, Wrapper
+
+
+class TDevNullTransport(TTransport.TTransportBase):
+  def __init__(self):
+    pass
+
+  def isOpen(self):
+    return True
+
+ooe1 = OneOfEach()
+ooe1.im_true = True
+ooe1.im_false = False
+ooe1.a_bite = 0xd6
+ooe1.integer16 = 27000
+ooe1.integer32 = 1 << 24
+ooe1.integer64 = 6000 * 1000 * 1000
+ooe1.double_precision = math.pi
+ooe1.some_characters = "Debug THIS!"
+ooe1.zomg_unicode = "\xd7\n\a\t"
+
+ooe2 = OneOfEach()
+ooe2.integer16 = 16
+ooe2.integer32 = 32
+ooe2.integer64 = 64
+ooe2.double_precision = (math.sqrt(5) + 1) / 2
+ooe2.some_characters = ":R (me going \"rrrr\")"
+ooe2.zomg_unicode = "\xd3\x80\xe2\x85\xae\xce\x9d\x20"\
+                    "\xd0\x9d\xce\xbf\xe2\x85\xbf\xd0\xbe"\
+                    "\xc9\xa1\xd0\xb3\xd0\xb0\xcf\x81\xe2\x84\x8e"\
+                    "\x20\xce\x91\x74\x74\xce\xb1\xe2\x85\xbd\xce\xba"\
+                    "\xc7\x83\xe2\x80\xbc"
+
+hm = HolyMoley(**{"big": [], "contain": set(), "bonks": {}})
+hm.big.append(ooe1)
+hm.big.append(ooe2)
+hm.big[0].a_bite = 0x22
+hm.big[1].a_bite = 0x22
+
+hm.contain.add(("and a one", "and a two"))
+hm.contain.add(("then a one, two", "three!", "FOUR!"))
+hm.contain.add(())
+
+hm.bonks["nothing"] = []
+hm.bonks["something"] = [
+  Bonk(**{"type": 1, "message": "Wait."}),
+  Bonk(**{"type": 2, "message": "What?"}),
+]
+hm.bonks["poe"] = [
+  Bonk(**{"type": 3, "message": "quoth"}),
+  Bonk(**{"type": 4, "message": "the raven"}),
+  Bonk(**{"type": 5, "message": "nevermore"}),
+]
+
+rs = RandomStuff()
+rs.a = 1
+rs.b = 2
+rs.c = 3
+rs.myintlist = range(20)
+rs.maps = {1: Wrapper(**{"foo": Empty()}), 2: Wrapper(**{"foo": Empty()})}
+rs.bigint = 124523452435
+rs.triple = 3.14
+
+# make sure this splits two buffers in a buffered protocol
+rshuge = RandomStuff()
+rshuge.myintlist = range(10000)
+
+my_zero = Srv.Janky_result(**{"success": 5})
+
+
+def check_write(o):
+  trans_fast = TTransport.TMemoryBuffer()
+  trans_slow = TTransport.TMemoryBuffer()
+  prot_fast = TBinaryProtocol.TBinaryProtocolAccelerated(trans_fast)
+  prot_slow = TBinaryProtocol.TBinaryProtocol(trans_slow)
+
+  o.write(prot_fast)
+  o.write(prot_slow)
+  ORIG = trans_slow.getvalue()
+  MINE = trans_fast.getvalue()
+  if ORIG != MINE:
+    print("mine: %s\norig: %s" % (repr(MINE), repr(ORIG)))
+
+
+def check_read(o):
+  prot = TBinaryProtocol.TBinaryProtocol(TTransport.TMemoryBuffer())
+  o.write(prot)
+
+  slow_version_binary = prot.trans.getvalue()
+
+  prot = TBinaryProtocol.TBinaryProtocolAccelerated(
+      TTransport.TMemoryBuffer(slow_version_binary))
+  c = o.__class__()
+  c.read(prot)
+  if c != o:
+    print("copy: ")
+    pprint(eval(repr(c)))
+    print("orig: ")
+    pprint(eval(repr(o)))
+
+  prot = TBinaryProtocol.TBinaryProtocolAccelerated(
+      TTransport.TBufferedTransport(
+        TTransport.TMemoryBuffer(slow_version_binary)))
+  c = o.__class__()
+  c.read(prot)
+  if c != o:
+    print("copy: ")
+    pprint(eval(repr(c)))
+    print("orig: ")
+    pprint(eval(repr(o)))
+
+
+def do_test():
+  check_write(hm)
+  check_read(HolyMoley())
+  no_set = deepcopy(hm)
+  no_set.contain = set()
+  check_read(no_set)
+  check_write(rs)
+  check_read(rs)
+  check_write(rshuge)
+  check_read(rshuge)
+  check_write(my_zero)
+  check_read(my_zero)
+  check_read(Backwards(**{"first_tag2": 4, "second_tag1": 2}))
+
+  # One case where the serialized form changes, but only superficially.
+  o = Backwards(**{"first_tag2": 4, "second_tag1": 2})
+  trans_fast = TTransport.TMemoryBuffer()
+  trans_slow = TTransport.TMemoryBuffer()
+  prot_fast = TBinaryProtocol.TBinaryProtocolAccelerated(trans_fast)
+  prot_slow = TBinaryProtocol.TBinaryProtocol(trans_slow)
+
+  o.write(prot_fast)
+  o.write(prot_slow)
+  ORIG = trans_slow.getvalue()
+  MINE = trans_fast.getvalue()
+  assert id(ORIG) != id(MINE)
+
+  prot = TBinaryProtocol.TBinaryProtocolAccelerated(TTransport.TMemoryBuffer())
+  o.write(prot)
+  prot = TBinaryProtocol.TBinaryProtocol(
+      TTransport.TMemoryBuffer(prot.trans.getvalue()))
+  c = o.__class__()
+  c.read(prot)
+  if c != o:
+    print("copy: ")
+    pprint(eval(repr(c)))
+    print("orig: ")
+    pprint(eval(repr(o)))
+
+
+def do_benchmark(iters=5000):
+  setup = """
+from __main__ import hm, rs, TDevNullTransport
+from thrift.protocol import TBinaryProtocol
+trans = TDevNullTransport()
+prot = TBinaryProtocol.TBinaryProtocol%s(trans)
+"""
+
+  setup_fast = setup % "Accelerated"
+  setup_slow = setup % ""
+
+  print("Starting Benchmarks")
+
+  print("HolyMoley Standard = %f" %
+        timeit.Timer('hm.write(prot)', setup_slow).timeit(number=iters))
+  print("HolyMoley Acceler. = %f" %
+        timeit.Timer('hm.write(prot)', setup_fast).timeit(number=iters))
+
+  print("FastStruct Standard = %f" %
+        timeit.Timer('rs.write(prot)', setup_slow).timeit(number=iters))
+  print("FastStruct Acceler. = %f" %
+        timeit.Timer('rs.write(prot)', setup_fast).timeit(number=iters))
+
+if __name__ == '__main__':
+  do_test()
+  do_benchmark()
diff --git a/test/py/RunClientServer.py b/test/py/RunClientServer.py
index f084a41..f83f557 100755
--- a/test/py/RunClientServer.py
+++ b/test/py/RunClientServer.py
@@ -37,6 +37,7 @@
 DEFAULT_LIBDIR_PY3 = os.path.join(ROOT_DIR, 'lib', 'py', 'build', 'lib')
 
 SCRIPTS = [
+  'FastbinaryTest.py',
   'TestFrozen.py',
   'TSimpleJSONProtocolTest.py',
   'SerializationTest.py',