diff --git a/src/allmydata/introducer/server.py b/src/allmydata/introducer/server.py
index 9c756fef1..ef3e3c6d7 100644
--- a/src/allmydata/introducer/server.py
+++ b/src/allmydata/introducer/server.py
@@ -1,4 +1,5 @@
 from past.builtins import long
+from six import ensure_str
 
 import time, os.path, textwrap
 from zope.interface import implementer
@@ -280,6 +281,7 @@ class IntroducerService(service.MultiService, Referenceable):
     def remote_subscribe_v2(self, subscriber, service_name, subscriber_info):
         self.log("introducer: subscription[%s] request at %s"
                  % (service_name, subscriber), umid="U3uzLg")
+        service_name = ensure_str(service_name)
         return self.add_subscriber(subscriber, service_name, subscriber_info)
 
     def add_subscriber(self, subscriber, service_name, subscriber_info):
@@ -303,6 +305,7 @@ class IntroducerService(service.MultiService, Referenceable):
         subscriber.notifyOnDisconnect(_remove)
 
         # now tell them about any announcements they're interested in
+        assert {type(service_name)} == set(type(k[0]) for k in self._announcements)
         announcements = set( [ ann_t
                                for idx,(ann_t,canary,ann,when)
                                in self._announcements.items()
diff --git a/src/allmydata/test/test_introducer.py b/src/allmydata/test/test_introducer.py
index f4d01b3d9..bdae11403 100644
--- a/src/allmydata/test/test_introducer.py
+++ b/src/allmydata/test/test_introducer.py
@@ -594,7 +594,7 @@ class SystemTest(SystemTestMixin, AsyncTestCase):
                 self.failUnlessEqual(cdc["outbound_message"], expected)
             # now check the web status, make sure it renders without error
             ir = introweb.IntroducerRoot(self.parent)
-            self.parent.nodeid = "NODEID"
+            self.parent.nodeid = b"NODEID"
             log.msg("_check1 done")
             return flattenString(None, ir._create_element())
         d.addCallback(_check1)
@@ -604,7 +604,7 @@ class SystemTest(SystemTestMixin, AsyncTestCase):
             self.assertIn(NICKNAME % "0", text) # a v2 client
             self.assertIn(NICKNAME % "1", text) # another v2 client
             for i in range(NUM_STORAGE):
-                self.assertIn(printable_serverids[i], text,
+                self.assertIn(ensure_text(printable_serverids[i]), text,
                                   (i,printable_serverids[i],text))
                 # make sure there isn't a double-base32ed string too
                 self.assertNotIn(idlib.nodeid_b2a(printable_serverids[i]), text,
@@ -644,7 +644,7 @@ class SystemTest(SystemTestMixin, AsyncTestCase):
             self.create_tub(self.central_portnum)
             newfurl = self.central_tub.registerReference(self.the_introducer,
                                                          furlFile=iff)
-            assert newfurl == self.introducer_furl
+            assert ensure_binary(newfurl) == self.introducer_furl
         d.addCallback(_restart_introducer_tub)
 
         d.addCallback(_wait_for_connected)
@@ -696,7 +696,7 @@ class SystemTest(SystemTestMixin, AsyncTestCase):
             self.the_introducer = introducer
             newfurl = self.central_tub.registerReference(self.the_introducer,
                                                          furlFile=iff)
-            assert newfurl == self.introducer_furl
+            assert ensure_binary(newfurl) == self.introducer_furl
         d.addCallback(_restart_introducer)
 
         d.addCallback(_wait_for_connected)
diff --git a/src/allmydata/web/introweb.py b/src/allmydata/web/introweb.py
index f57a5232a..171c155d7 100644
--- a/src/allmydata/web/introweb.py
+++ b/src/allmydata/web/introweb.py
@@ -105,7 +105,7 @@ class IntroducerRootElement(Element):
             if ad.service_name not in services:
                 services[ad.service_name] = 0
             services[ad.service_name] += 1
-        service_names = services.keys()
+        service_names = list(services.keys())
         service_names.sort()
         return u", ".join(u"{}: {}".format(service_name, services[service_name])
                           for service_name in service_names)