diff --git a/src/allmydata/test/common.py b/src/allmydata/test/common.py
index ff31ea939..e7a94ff40 100644
--- a/src/allmydata/test/common.py
+++ b/src/allmydata/test/common.py
@@ -4,6 +4,7 @@ __all__ = [
     "SyncTestCase",
     "AsyncTestCase",
     "AsyncBrokenTestCase",
+    "TrialTestCase",
 
     "flush_logged_errors",
     "skip",
@@ -11,6 +12,7 @@ __all__ = [
 ]
 
 import os, random, struct
+import six
 import tempfile
 from tempfile import mktemp
 from functools import partial
@@ -57,6 +59,7 @@ from twisted.internet.interfaces import (
     IReactorSocket,
 )
 from twisted.internet.endpoints import AdoptedStreamServerEndpoint
+from twisted.trial.unittest import TestCase as _TrialTestCase
 
 from allmydata import uri
 from allmydata.interfaces import IMutableFileNode, IImmutableFileNode,\
@@ -1242,3 +1245,29 @@ class AsyncBrokenTestCase(_TestCaseMixin, TestCase):
     run_tests_with = EliotLoggedRunTest.make_factory(
         AsynchronousDeferredRunTestForBrokenTwisted.make_factory(timeout=60.0),
     )
+
+
+class TrialTestCase(_TrialTestCase):
+    """
+    A twisted.trial.unittest.TestCaes with Tahoe required fixes
+    applied. Currently these are:
+
+      - ensure that .fail() passes a bytes msg on Python2
+    """
+
+    def fail(self, msg):
+        """
+        Ensure our msg is a native string on Python2. If it was Unicode,
+        we encode it as utf8 and hope for the best. On Python3 we take
+        no action.
+
+        This is necessary because Twisted passes the 'msg' argument
+        along to the constructor of an exception; on Python2,
+        Exception will accept a `unicode` instance but will fail if
+        you try to turn that Exception instance into a string.
+        """
+
+        if six.PY2:
+            if isinstance(msg, six.text_type):
+                return super(self, TrialTestCase).fail(msg.encode("utf8"))
+        return super(self, TrialTestCase).fail(msg)
diff --git a/src/allmydata/test/web/common.py b/src/allmydata/test/web/common.py
index 15743bb92..871cdeb26 100644
--- a/src/allmydata/test/web/common.py
+++ b/src/allmydata/test/web/common.py
@@ -28,9 +28,8 @@ def assert_soup_has_tag_with_attributes(testcase, soup, tag_name, attrs):
     for tag in tags:
         if all(v in tag.attrs.get(k, []) for k, v in attrs.items()):
             return  # we found every attr in this tag; done
-    # seems like exceptions can't support unicode text in python2??
     testcase.fail(
-        "No <{}> tags contain attributes: {}".format(tag_name, attrs)
+        u"No <{}> tags contain attributes: {}".format(tag_name, attrs)
     )
 
 
@@ -72,9 +71,8 @@ def assert_soup_has_tag_with_content(testcase, soup, tag_name, content):
 
         if content in _normalized_contents(tag):
             return
-    # seems like exceptions can't support unicode text in python2??
     testcase.fail(
-        "No <{}> tag contains the text '{}'".format(tag_name, content).encode('utf8')
+        u"No <{}> tag contains the text '{}'".format(tag_name, content)
     )
 
 
diff --git a/src/allmydata/test/web/test_web.py b/src/allmydata/test/web/test_web.py
index 1e36b6a21..191ffbdef 100644
--- a/src/allmydata/test/web/test_web.py
+++ b/src/allmydata/test/web/test_web.py
@@ -8,7 +8,6 @@ import mock
 from bs4 import BeautifulSoup
 
 from twisted.application import service
-from twisted.trial import unittest
 from twisted.internet import defer
 from twisted.internet.defer import inlineCallbacks, returnValue, maybeDeferred
 from twisted.internet.task import Clock
@@ -50,6 +49,7 @@ from ..common import (
     WebErrorMixin,
     make_mutable_file_uri,
     create_mutable_filenode,
+    TrialTestCase,
 )
 from .common import (
     assert_soup_has_favicon,
@@ -681,7 +681,7 @@ class WebMixin(testutil.TimezoneMixin):
 
 
 
-class MultiFormatPageTests(unittest.TestCase):
+class MultiFormatPageTests(TrialTestCase):
     """
     Tests for ``MultiFormatPage``.
     """
@@ -790,7 +790,7 @@ class MultiFormatPageTests(unittest.TestCase):
 
 
 
-class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixin, unittest.TestCase):
+class Web(WebMixin, WebErrorMixin, testutil.StallMixin, testutil.ReallyEqualMixin, TrialTestCase):
     maxDiff = None
 
     def test_create(self):