diff --git a/postorius/Dockerfile b/postorius/Dockerfile
index fb619d4..6357a3b 100644
--- a/postorius/Dockerfile
+++ b/postorius/Dockerfile
@@ -16,8 +16,7 @@ RUN set -ex \
 	&& apk add --no-cache --virtual .mailman-rundeps bash \
 	   postgresql-client mysql-client py-mysqldb curl mailcap \
 	&& pip install -U Django>=1.11 pip \
-	&& pip install postorius>=1.2.0a1 \
-		django-mailman3>=1.2.0a2 \
+	&& pip install postorius==1.2.0a1 \
 		uwsgi \
 		psycopg2 \
 		dj-database-url \
diff --git a/postorius/mailman-web/settings.py b/postorius/mailman-web/settings.py
index 4f4bf00..dbf8092 100644
--- a/postorius/mailman-web/settings.py
+++ b/postorius/mailman-web/settings.py
@@ -58,13 +58,12 @@ ALLOWED_HOSTS = [
 ]
 
 # Try to get the address of Mailman Core automatically.
-MAILMAN_HOST_IP_AUTO = socket.gethostbyname('mailman-core')
 
 # Mailman API credentials
 MAILMAN_REST_API_URL = os.environ.get('MAILMAN_REST_URL', 'http://mailman-core:8001')
 MAILMAN_REST_API_USER = os.environ.get('MAILMAN_REST_USER', 'restadmin')
 MAILMAN_REST_API_PASS = os.environ.get('MAILMAN_REST_PASSWORD', 'restpass')
-MAILMAN_ARCHIVER_FROM = (MAILMAN_HOST_IP_AUTO, os.environ.get('MAILMAN_HOST_IP', '172.19.199.2'))
+MAILMAN_ARCHIVER_FROM = os.environ.get('MAILMAN_HOST_IP', '172.19.199.2')
 
 # Application definition
 
@@ -92,7 +91,7 @@ INSTALLED_APPS = (
     'allauth.socialaccount.providers.google',
 )
 
-_MIDDLEWARE = (
+MIDDLEWARE = (
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.middleware.common.CommonMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',
@@ -106,17 +105,8 @@ _MIDDLEWARE = (
     'postorius.middleware.PostoriusMiddleware',
 )
 
-# Use old-style Middleware class in Python 2 and released versions of
-# Django-mailman3 don't support new style middlewares.
-
-if sys.version_info < (3, 0):
-    MIDDLEWARE_CLASSES = _MIDDLEWARE
-else:
-    MIDDLEWARE = _MIDDLEWARE
-
 ROOT_URLCONF = 'urls'
 
-
 TEMPLATES = [
     {
         'BACKEND': 'django.template.backends.django.DjangoTemplates',
diff --git a/postorius/mailman-web/urls.py b/postorius/mailman-web/urls.py
index d398308..e7bb6be 100644
--- a/postorius/mailman-web/urls.py
+++ b/postorius/mailman-web/urls.py
@@ -17,8 +17,9 @@
 # Postorius.  If not, see <http://www.gnu.org/licenses/>.
 
 
-from django.conf.urls import include, url, reverse_lazy
+from django.conf.urls import include, url
 from django.contrib import admin
+from django.urls import reverse_lazy
 from django.views.generic import RedirectView
 
 urlpatterns = [