diff --git a/acme/acme/challenges.py b/acme/acme/challenges.py
index 493d230d8..3fa259b13 100644
--- a/acme/acme/challenges.py
+++ b/acme/acme/challenges.py
@@ -271,8 +271,8 @@ class DNS01(KeyAuthorizationChallenge):
         :rtype: unicode
 
         """
-        return jose.b64encode(hashlib.sha256(
-            self.key_authorization(account_key)).digest())
+        return jose.b64encode(hashlib.sha256(self.key_authorization(
+            account_key).encode("utf-8")).digest()).decode()
 
     def validation_domain_name(self, name):
         """Domain name for TXT validation record.
diff --git a/acme/setup.py b/acme/setup.py
index c54dc42e6..df5cfba0e 100644
--- a/acme/setup.py
+++ b/acme/setup.py
@@ -35,9 +35,14 @@ if sys.version_info < (2, 7, 9):
     install_requires.append('ndg-httpsclient')
     install_requires.append('pyasn1')
 
-dns_extras = [
-    'dnspython',
-]
+if sys.version_info < (3, 0):
+    dns_extras = [
+        'dnspython',
+    ]
+else:
+    dns_extras = [
+        'dnspython3',
+    ]
 
 docs_extras = [
     'Sphinx>=1.0',  # autodoc_member_order = 'bysource', autodoc_default_flags