diff --git a/modoboa/core/tests/test_views.py b/modoboa/core/tests/test_views.py
index aa09458de..904754fc3 100644
--- a/modoboa/core/tests/test_views.py
+++ b/modoboa/core/tests/test_views.py
@@ -31,7 +31,7 @@ class LoginTestCase(ModoTestCase):
         signals.get_announcements.connect(announcement)
         response = self.client.get(reverse("core:login"))
         self.assertEqual(response.status_code, 200)
-        self.assertIn("This is an annoucement!", response.content)
+        self.assertIn("This is an annoucement!", str(response.content))
 
 
 class DashboardTestCase(ModoTestCase):
@@ -53,12 +53,12 @@ class DashboardTestCase(ModoTestCase):
         url = reverse("core:dashboard")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 200)
-        self.assertIn("Latest news", response.content)
+        self.assertIn("Latest news", str(response.content))
         self.client.logout()
         self.client.login(username=self.dadmin.username, password="toto")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 200)
-        self.assertIn("Latest news", response.content)
+        self.assertIn("Latest news", str(response.content))
         self.client.logout()
         self.client.login(username=self.user.username, password="toto")
         response = self.client.get(url)
@@ -102,7 +102,7 @@ class DashboardTestCase(ModoTestCase):
         url = reverse("core:top_notifications_check")
         response = self.client.get(url)
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(len(json.loads(response.content)), 1)
+        self.assertEqual(len(response.json()), 1)
 
 
 class SettingsTestCase(ModoTestCase):
diff --git a/modoboa/lib/authbackends.py b/modoboa/lib/authbackends.py
index 59d46678e..df9894f1e 100644
--- a/modoboa/lib/authbackends.py
+++ b/modoboa/lib/authbackends.py
@@ -16,11 +16,6 @@ class SMTPBackend(object):
 
     def authenticate(self, username=None, password=None):
         """Check the username/password and return a User."""
-        if type(username) is unicode:
-            username = username.encode("utf-8")
-        if type(password) is unicode:
-            password = password.encode("utf-8")
-
         host = getattr(settings, "AUTH_SMTP_SERVER_ADDRESS", "localhost")
         port = getattr(settings, "AUTH_SMTP_SERVER_PORT", 25)
         secured_mode = getattr(settings, "AUTH_SMTP_SECURED_MODE", None)
diff --git a/modoboa/lib/tests.py b/modoboa/lib/tests.py
index 99d6186d1..7cb122345 100644
--- a/modoboa/lib/tests.py
+++ b/modoboa/lib/tests.py
@@ -66,7 +66,7 @@ class ModoTestCase(ParametersMixin, TestCase):
         response = getattr(self.client, method)(
             url, params, HTTP_X_REQUESTED_WITH='XMLHttpRequest')
         self.assertEqual(response.status_code, status)
-        return json.loads(response.content)
+        return response.json()
 
     def ajax_post(self, *args, **kwargs):
         return self.ajax_request('post', *args, **kwargs)