diff --git a/src/allmydata/test/common.py b/src/allmydata/test/common.py
index c28db9191..8d50390e4 100644
--- a/src/allmydata/test/common.py
+++ b/src/allmydata/test/common.py
@@ -432,7 +432,7 @@ class FakeCHKFileNode(object):  # type: ignore # incomplete implementation
         return self.storage_index
 
     def check(self, monitor, verify=False, add_lease=False):
-        s = StubServer("\x00"*20)
+        s = StubServer(b"\x00"*20)
         r = CheckResults(self.my_uri, self.storage_index,
                          healthy=True, recoverable=True,
                          count_happiness=10,
diff --git a/src/allmydata/test/web/test_web.py b/src/allmydata/test/web/test_web.py
index 203585b42..8ed7de880 100644
--- a/src/allmydata/test/web/test_web.py
+++ b/src/allmydata/test/web/test_web.py
@@ -3178,7 +3178,7 @@ class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixi
     def test_POST_DIRURL_check_and_repair(self):
         foo_url = self.public_url + "/foo"
         res = yield self.POST(foo_url, t="check", repair="true")
-        self.failUnlessIn("Healthy :", res)
+        self.failUnlessIn(b"Healthy :", res)
 
         redir_url = "http://allmydata.org/TARGET"
         body, headers = self.build_form(t="check", repair="true",
@@ -3187,6 +3187,7 @@ class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixi
                                     method="post", data=body, headers=headers,
                                     code=http.FOUND)
         res = yield self.POST(foo_url, t="check", return_to=redir_url)
+        res = unicode(res, "utf-8")
         self.failUnlessIn("Healthy :", res)
         self.failUnlessIn("Return to file/directory", res)
         self.failUnlessIn(redir_url, res)
@@ -3195,9 +3196,9 @@ class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixi
         quux_url = "/uri/%s" % urlquote(self._quux_txt_uri)
         d = self.POST(quux_url, t="check")
         def _check(res):
-            self.failUnlessIn("Healthy", res)
+            self.failUnlessIn(b"Healthy", res)
         d.addCallback(_check)
-        quux_extension_url = "/uri/%s" % urlquote("%s:3:131073" % self._quux_txt_uri)
+        quux_extension_url = "/uri/%s" % urlquote("%s:3:131073" % unicode(self._quux_txt_uri, "utf-8"))
         d.addCallback(lambda ignored:
                       self.POST(quux_extension_url, t="check"))
         d.addCallback(_check)
@@ -3264,15 +3265,15 @@ class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixi
         self.failUnlessReallyEqual(data["count-objects-healthy"], 11)
 
         res = yield self.get_operation_results(None, "123", "html")
-        self.failUnlessIn("Objects Checked: <span>11</span>", res)
-        self.failUnlessIn("Objects Healthy: <span>11</span>", res)
+        self.failUnlessIn(b"Objects Checked: <span>11</span>", res)
+        self.failUnlessIn(b"Objects Healthy: <span>11</span>", res)
         soup = BeautifulSoup(res, 'html5lib')
         assert_soup_has_favicon(self, soup)
 
         res = yield self.GET("/operations/123/")
         # should be the same as without the slash
-        self.failUnlessIn("Objects Checked: <span>11</span>", res)
-        self.failUnlessIn("Objects Healthy: <span>11</span>", res)
+        self.failUnlessIn(b"Objects Checked: <span>11</span>", res)
+        self.failUnlessIn(b"Objects Healthy: <span>11</span>", res)
         soup = BeautifulSoup(res, 'html5lib')
         assert_soup_has_favicon(self, soup)
 
@@ -3282,9 +3283,9 @@ class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixi
 
         foo_si = self._foo_node.get_storage_index()
         foo_si_s = base32.b2a(foo_si)
-        res = yield self.GET("/operations/123/%s?output=JSON" % foo_si_s)
+        res = yield self.GET("/operations/123/%s?output=JSON" % unicode(foo_si_s, "ascii"))
         data = json.loads(res)
-        self.failUnlessEqual(data["storage-index"], foo_si_s)
+        self.failUnlessEqual(data["storage-index"], unicode(foo_si_s, "ascii"))
         self.failUnless(data["results"]["healthy"])
 
     def test_POST_DIRURL_deepcheck_and_repair(self):
@@ -4261,6 +4262,7 @@ class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixi
                  http.FOUND,
                  http.TEMPORARY_REDIRECT,
                  ] if code is None else [code]
+        body = yield response.content()
         self.assertIn(response.code, codes)
         location = response.headers.getRawHeaders(b"location")[0]
         if target_location is not None:
diff --git a/src/allmydata/web/check_results.py b/src/allmydata/web/check_results.py
index 54130183b..e3de4a7ce 100644
--- a/src/allmydata/web/check_results.py
+++ b/src/allmydata/web/check_results.py
@@ -432,7 +432,7 @@ class DeepCheckResultsRenderer(MultiFormatResource):
             return CheckResultsRenderer(self._client,
                                         r.get_results_for_storage_index(si))
         except KeyError:
-            raise WebError("No detailed results for SI %s" % html.escape(name),
+            raise WebError("No detailed results for SI %s" % html.escape(str(name, "utf-8")),
                            http.NOT_FOUND)
 
     @render_exception
diff --git a/src/allmydata/web/operations.py b/src/allmydata/web/operations.py
index ca6826169..6769fb044 100644
--- a/src/allmydata/web/operations.py
+++ b/src/allmydata/web/operations.py
@@ -1,3 +1,4 @@
+from past.builtins import unicode
 
 import time
 from hyperlink import (
@@ -106,7 +107,7 @@ class OphandleTable(resource.Resource, service.Service):
         (monitor, renderer, when_added) = self.handles[ophandle]
 
         t = get_arg(req, "t", "status")
-        if t == "cancel" and req.method == b"POST":
+        if t == b"cancel" and req.method == b"POST":
             monitor.cancel()
             # return the status anyways, but release the handle
             self._release_ophandle(ophandle)
@@ -151,7 +152,7 @@ class ReloadMixin(object):
     @renderer
     def refresh(self, req, tag):
         if self.monitor.is_finished():
-            return ""
+            return b""
         tag.attributes["http-equiv"] = "refresh"
         tag.attributes["content"] = str(self.REFRESH_TIME)
         return tag
diff --git a/src/allmydata/webish.py b/src/allmydata/webish.py
index e90fa573a..c3965645a 100644
--- a/src/allmydata/webish.py
+++ b/src/allmydata/webish.py
@@ -211,7 +211,7 @@ class WebishServer(service.MultiService):
         # use to test ophandle expiration.
         self._operations = OphandleTable(clock)
         self._operations.setServiceParent(self)
-        self.root.putChild("operations", self._operations)
+        self.root.putChild(b"operations", self._operations)
 
         self.root.putChild(b"storage-plugins", StoragePlugins(client))
 
@@ -220,7 +220,7 @@ class WebishServer(service.MultiService):
         self.site = TahoeLAFSSite(tempdir, self.root)
         self.staticdir = staticdir # so tests can check
         if staticdir:
-            self.root.putChild("static", static.File(staticdir))
+            self.root.putChild(b"static", static.File(staticdir))
         if re.search(r'^\d', webport):
             webport = "tcp:"+webport # twisted warns about bare "0" or "3456"
         # strports must be native strings.