diff --git a/src/allmydata/immutable/downloader/share.py b/src/allmydata/immutable/downloader/share.py
index 7ec2935fd..15f55d409 100644
--- a/src/allmydata/immutable/downloader/share.py
+++ b/src/allmydata/immutable/downloader/share.py
@@ -464,7 +464,7 @@ class Share(object):
         # there was corruption somewhere in the given range
         reason = "corruption in share[%d-%d): %s" % (start, start+offset,
                                                      str(f.value))
-        self._rref.callRemoteOnly("advise_corrupt_share", reason)
+        self._rref.callRemoteOnly("advise_corrupt_share", reason.encode("utf-8"))
 
     def _satisfy_block_hash_tree(self, needed_hashes):
         o_bh = self.actual_offsets["block_hashes"]
diff --git a/src/allmydata/mutable/retrieve.py b/src/allmydata/mutable/retrieve.py
index b2d234a15..fde762d29 100644
--- a/src/allmydata/mutable/retrieve.py
+++ b/src/allmydata/mutable/retrieve.py
@@ -39,7 +39,7 @@ class RetrieveStatus(object):
         self.size = None
         self.status = "Not started"
         self.progress = 0.0
-        self.counter = self.statusid_counter.next()
+        self.counter = next(self.statusid_counter)
         self.started = time.time()
 
     def get_started(self):
@@ -321,7 +321,7 @@ class Retrieve(object):
         self._active_readers = [] # list of active readers for this dl.
         self._block_hash_trees = {} # shnum => hashtree
 
-        for i in xrange(self._total_shares):
+        for i in range(self._total_shares):
             # So we don't have to do this later.
             self._block_hash_trees[i] = hashtree.IncompleteHashTree(self._num_segments)
 
diff --git a/src/allmydata/mutable/servermap.py b/src/allmydata/mutable/servermap.py
index 8dba6d8b5..32962c495 100644
--- a/src/allmydata/mutable/servermap.py
+++ b/src/allmydata/mutable/servermap.py
@@ -33,7 +33,7 @@ class UpdateStatus(object):
         self.mode = "?"
         self.status = "Not started"
         self.progress = 0.0
-        self.counter = self.statusid_counter.next()
+        self.counter = next(self.statusid_counter)
         self.started = time.time()
         self.finished = None
 
diff --git a/src/allmydata/storage/server.py b/src/allmydata/storage/server.py
index 14eb08f84..8a8138f26 100644
--- a/src/allmydata/storage/server.py
+++ b/src/allmydata/storage/server.py
@@ -697,7 +697,7 @@ class StorageServer(service.MultiService, Referenceable):
         # This is a remote API, I believe, so this has to be bytes for legacy
         # protocol backwards compatibility reasons.
         assert isinstance(share_type, bytes)
-        assert isinstance(reason, bytes)
+        assert isinstance(reason, bytes), "%r is not bytes" % (reason,)
         fileutil.make_dirs(self.corruption_advisory_dir)
         now = time_format.iso_utc(sep="T")
         si_s = si_b2a(storage_index)
diff --git a/src/allmydata/test/test_download.py b/src/allmydata/test/test_download.py
index a65b627d3..bbf1ab75c 100644
--- a/src/allmydata/test/test_download.py
+++ b/src/allmydata/test/test_download.py
@@ -1,6 +1,6 @@
 from __future__ import print_function
 
-from future.utils import bchr, bord
+from future.utils import bchr
 
 # system-level upload+download roundtrip test, but using shares created from
 # a previous run. This asserts that the current code is capable of decoding
@@ -35,7 +35,7 @@ mutable_plaintext = b"This is a moderate-sized mutable file.\n" * 10
 # this chunk was generated by create_share(), written to disk, then pasted
 # into this file. These shares were created by 1.2.0-r3247, a version that's
 # probably fairly close to 1.3.0 .
-#--------- BEGIN stored_shares.py --------------
+#--------- BEGIN stored_shares.py --------------r
 immutable_uri = b"URI:CHK:g4i6qkk7mlj4vkl5ncg6dwo73i:qcas2ebousfk3q5rkl2ncayeku52kpyse76v5yeel2t2eaa4f6ha:3:10:310"
 immutable_shares = {
  0: { # client[0]
@@ -120,7 +120,7 @@ class _Base(GridTestMixin, ShouldFailMixin):
         d.addCallback(lambda ignored:
                       self.c0.create_mutable_file(mutable_plaintext))
         def _created_mutable(n):
-            f.write('mutable_uri = "%s"\n' % n.get_uri())
+            f.write('mutable_uri = b"%s"\n' % n.get_uri())
             f.write('mutable_shares = {\n')
             si = uri.from_string(n.get_uri()).get_storage_index()
             si_dir = storage_index_to_dir(si)
@@ -604,8 +604,8 @@ class DownloadTest(_Base, unittest.TestCase):
         # the share. This exercises a different code path.
         for s in self.c0.storage_broker.get_connected_servers():
             v = s.get_version()
-            v1 = v["http://allmydata.org/tahoe/protocols/storage/v1"]
-            v1["tolerates-immutable-read-overrun"] = False
+            v1 = v[b"http://allmydata.org/tahoe/protocols/storage/v1"]
+            v1[b"tolerates-immutable-read-overrun"] = False
 
         n = self.c0.create_node_from_uri(immutable_uri)
         d = download_to_data(n)
@@ -1138,7 +1138,7 @@ class Corruption(_Base, unittest.TestCase):
 
     def _corrupt_flip_all(self, ign, imm_uri, which):
         def _corruptor(s, debug=False):
-            return s[:which] + chr(ord(s[which:which+1])^0x01) + s[which+1:]
+            return s[:which] + bchr(ord(s[which:which+1])^0x01) + s[which+1:]
         self.corrupt_all_shares(imm_uri, _corruptor)
 
 class DownloadV2(_Base, unittest.TestCase):