diff --git a/src/postorius/tests/fixtures/vcr_cassettes/mailman_user_none_prefs.yaml b/src/postorius/tests/fixtures/vcr_cassettes/mailman_user_none_prefs.yaml
new file mode 100644
index 0000000..3c5401e
--- /dev/null
+++ b/src/postorius/tests/fixtures/vcr_cassettes/mailman_user_none_prefs.yaml
@@ -0,0 +1,357 @@
+interactions:
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/lists/foo.example.com
+  response:
+    body: {string: !!python/unicode '{"display_name": "Foo", "fqdn_listname": "foo@example.com",
+        "http_etag": "\"698a819bbb6b902096a8c5543cc7fac2328960d5\"", "list_id": "foo.example.com",
+        "list_name": "foo", "mail_host": "example.com", "member_count": 0, "self_link":
+        "http://localhost:9001/3.0/lists/foo.example.com", "volume": 1}'}
+    headers:
+      content-length: ['294']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: display_name=None&list_id=foo.example.com&pre_approved=True&pre_confirmed=True&pre_verified=True&subscriber=user%40example.com
+    headers:
+      accept-encoding: ['gzip, deflate']
+      !!python/unicode content-type: [!!python/unicode application/x-www-form-urlencoded]
+    method: !!python/unicode POST
+    uri: http://localhost:9001/3.0/members
+  response:
+    body: {string: !!python/unicode ''}
+    headers:
+      content-length: ['0']
+      location: ['http://localhost:9001/3.0/members/1']
+    status: {code: 201, message: Created}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/user@example.com
+  response:
+    body: {string: !!python/unicode '{"created_on": "2005-08-01T07:49:23", "http_etag":
+        "\"ef76f3eeb810f6a24e4157eb493e81b8dbf76260\"", "is_server_owner": false,
+        "password": "$6$rounds=640174$Aw8ypj2F6ngmjWkv$B.xNJDSwm0TzBmtsRsSmvswdu1oeEl2uaaA1NbiL83E8ylEycVikTdZsLv/C9/MO9Qbpr4M3mDYVXiTEmM.dp.",
+        "self_link": "http://localhost:9001/3.0/users/1", "user_id": 1}'}
+    headers:
+      content-length: ['324']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/addresses
+  response:
+    body: {string: !!python/unicode '{"entries": [{"email": "user@example.com", "http_etag":
+        "\"52ace72a40745c0e003216ad8fbeb62bbf38e072\"", "original_email": "user@example.com",
+        "registered_on": "2005-08-01T07:49:23", "self_link": "http://localhost:9001/3.0/addresses/user@example.com",
+        "user": "http://localhost:9001/3.0/users/1", "verified_on": "2005-08-01T07:49:23"}],
+        "http_etag": "\"9580a3b8be6093d25a53e0656b32438452dabdbd\"", "start": 0, "total_size":
+        1}'}
+    headers:
+      content-length: ['425']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/user@example.com
+  response:
+    body: {string: !!python/unicode '{"created_on": "2005-08-01T07:49:23", "http_etag":
+        "\"ef76f3eeb810f6a24e4157eb493e81b8dbf76260\"", "is_server_owner": false,
+        "password": "$6$rounds=640174$Aw8ypj2F6ngmjWkv$B.xNJDSwm0TzBmtsRsSmvswdu1oeEl2uaaA1NbiL83E8ylEycVikTdZsLv/C9/MO9Qbpr4M3mDYVXiTEmM.dp.",
+        "self_link": "http://localhost:9001/3.0/users/1", "user_id": 1}'}
+    headers:
+      content-length: ['324']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/preferences
+  response:
+    body: {string: !!python/unicode '{"http_etag": "\"b74f203eb6bb291486b3f3f98887098a7bec7de8\"",
+        "self_link": "http://localhost:9001/3.0/users/1/preferences"}'}
+    headers:
+      content-length: ['123']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/user@example.com
+  response:
+    body: {string: !!python/unicode '{"created_on": "2005-08-01T07:49:23", "http_etag":
+        "\"ef76f3eeb810f6a24e4157eb493e81b8dbf76260\"", "is_server_owner": false,
+        "password": "$6$rounds=640174$Aw8ypj2F6ngmjWkv$B.xNJDSwm0TzBmtsRsSmvswdu1oeEl2uaaA1NbiL83E8ylEycVikTdZsLv/C9/MO9Qbpr4M3mDYVXiTEmM.dp.",
+        "self_link": "http://localhost:9001/3.0/users/1", "user_id": 1}'}
+    headers:
+      content-length: ['324']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/addresses
+  response:
+    body: {string: !!python/unicode '{"entries": [{"email": "user@example.com", "http_etag":
+        "\"52ace72a40745c0e003216ad8fbeb62bbf38e072\"", "original_email": "user@example.com",
+        "registered_on": "2005-08-01T07:49:23", "self_link": "http://localhost:9001/3.0/addresses/user@example.com",
+        "user": "http://localhost:9001/3.0/users/1", "verified_on": "2005-08-01T07:49:23"}],
+        "http_etag": "\"9580a3b8be6093d25a53e0656b32438452dabdbd\"", "start": 0, "total_size":
+        1}'}
+    headers:
+      content-length: ['425']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/lists/foo.example.com
+  response:
+    body: {string: !!python/unicode '{"display_name": "Foo", "fqdn_listname": "foo@example.com",
+        "http_etag": "\"98cc998d4a30293ec17da639bce10617912a6e1e\"", "list_id": "foo.example.com",
+        "list_name": "foo", "mail_host": "example.com", "member_count": 1, "self_link":
+        "http://localhost:9001/3.0/lists/foo.example.com", "volume": 1}'}
+    headers:
+      content-length: ['294']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/user@example.com
+  response:
+    body: {string: !!python/unicode '{"created_on": "2005-08-01T07:49:23", "http_etag":
+        "\"ef76f3eeb810f6a24e4157eb493e81b8dbf76260\"", "is_server_owner": false,
+        "password": "$6$rounds=640174$Aw8ypj2F6ngmjWkv$B.xNJDSwm0TzBmtsRsSmvswdu1oeEl2uaaA1NbiL83E8ylEycVikTdZsLv/C9/MO9Qbpr4M3mDYVXiTEmM.dp.",
+        "self_link": "http://localhost:9001/3.0/users/1", "user_id": 1}'}
+    headers:
+      content-length: ['324']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/addresses
+  response:
+    body: {string: !!python/unicode '{"entries": [{"email": "user@example.com", "http_etag":
+        "\"52ace72a40745c0e003216ad8fbeb62bbf38e072\"", "original_email": "user@example.com",
+        "registered_on": "2005-08-01T07:49:23", "self_link": "http://localhost:9001/3.0/addresses/user@example.com",
+        "user": "http://localhost:9001/3.0/users/1", "verified_on": "2005-08-01T07:49:23"}],
+        "http_etag": "\"9580a3b8be6093d25a53e0656b32438452dabdbd\"", "start": 0, "total_size":
+        1}'}
+    headers:
+      content-length: ['425']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: subscriber=user%40example.com
+    headers:
+      accept-encoding: ['gzip, deflate']
+      !!python/unicode content-type: [!!python/unicode application/x-www-form-urlencoded]
+    method: !!python/unicode POST
+    uri: http://localhost:9001/3.0/members/find
+  response:
+    body: {string: !!python/unicode '{"entries": [{"address": "http://localhost:9001/3.0/addresses/user@example.com",
+        "delivery_mode": "regular", "email": "user@example.com", "http_etag": "\"daa2142986cd1722628e6cdc494b6649d7e635f4\"",
+        "list_id": "foo.example.com", "member_id": 1, "moderation_action": "defer",
+        "role": "member", "self_link": "http://localhost:9001/3.0/members/1", "user":
+        "http://localhost:9001/3.0/users/1"}], "http_etag": "\"507c947b2e96fe6b2037a446f6d9897e0707b684\"",
+        "start": 0, "total_size": 1}'}
+    headers:
+      content-length: ['481']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/members/1/preferences
+  response:
+    body: {string: !!python/unicode '{"http_etag": "\"4747934e4e9b7e99c3faf1c663491719cbfe2dd0\"",
+        "self_link": "http://localhost:9001/3.0/members/1/preferences"}'}
+    headers:
+      content-length: ['125']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/user@example.com
+  response:
+    body: {string: !!python/unicode '{"created_on": "2005-08-01T07:49:23", "http_etag":
+        "\"ef76f3eeb810f6a24e4157eb493e81b8dbf76260\"", "is_server_owner": false,
+        "password": "$6$rounds=640174$Aw8ypj2F6ngmjWkv$B.xNJDSwm0TzBmtsRsSmvswdu1oeEl2uaaA1NbiL83E8ylEycVikTdZsLv/C9/MO9Qbpr4M3mDYVXiTEmM.dp.",
+        "self_link": "http://localhost:9001/3.0/users/1", "user_id": 1}'}
+    headers:
+      content-length: ['324']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/addresses
+  response:
+    body: {string: !!python/unicode '{"entries": [{"email": "user@example.com", "http_etag":
+        "\"52ace72a40745c0e003216ad8fbeb62bbf38e072\"", "original_email": "user@example.com",
+        "registered_on": "2005-08-01T07:49:23", "self_link": "http://localhost:9001/3.0/addresses/user@example.com",
+        "user": "http://localhost:9001/3.0/users/1", "verified_on": "2005-08-01T07:49:23"}],
+        "http_etag": "\"9580a3b8be6093d25a53e0656b32438452dabdbd\"", "start": 0, "total_size":
+        1}'}
+    headers:
+      content-length: ['425']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/user@example.com
+  response:
+    body: {string: !!python/unicode '{"created_on": "2005-08-01T07:49:23", "http_etag":
+        "\"ef76f3eeb810f6a24e4157eb493e81b8dbf76260\"", "is_server_owner": false,
+        "password": "$6$rounds=640174$Aw8ypj2F6ngmjWkv$B.xNJDSwm0TzBmtsRsSmvswdu1oeEl2uaaA1NbiL83E8ylEycVikTdZsLv/C9/MO9Qbpr4M3mDYVXiTEmM.dp.",
+        "self_link": "http://localhost:9001/3.0/users/1", "user_id": 1}'}
+    headers:
+      content-length: ['324']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/addresses
+  response:
+    body: {string: !!python/unicode '{"entries": [{"email": "user@example.com", "http_etag":
+        "\"52ace72a40745c0e003216ad8fbeb62bbf38e072\"", "original_email": "user@example.com",
+        "registered_on": "2005-08-01T07:49:23", "self_link": "http://localhost:9001/3.0/addresses/user@example.com",
+        "user": "http://localhost:9001/3.0/users/1", "verified_on": "2005-08-01T07:49:23"}],
+        "http_etag": "\"9580a3b8be6093d25a53e0656b32438452dabdbd\"", "start": 0, "total_size":
+        1}'}
+    headers:
+      content-length: ['425']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/addresses/user@example.com/preferences
+  response:
+    body: {string: !!python/unicode '{"http_etag": "\"c557a0cd7d400f67152a6f6e5e2c14858e632323\"",
+        "self_link": "http://localhost:9001/3.0/addresses/user@example.com/preferences"}'}
+    headers:
+      content-length: ['142']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/user@example.com
+  response:
+    body: {string: !!python/unicode '{"created_on": "2005-08-01T07:49:23", "http_etag":
+        "\"ef76f3eeb810f6a24e4157eb493e81b8dbf76260\"", "is_server_owner": false,
+        "password": "$6$rounds=640174$Aw8ypj2F6ngmjWkv$B.xNJDSwm0TzBmtsRsSmvswdu1oeEl2uaaA1NbiL83E8ylEycVikTdZsLv/C9/MO9Qbpr4M3mDYVXiTEmM.dp.",
+        "self_link": "http://localhost:9001/3.0/users/1", "user_id": 1}'}
+    headers:
+      content-length: ['324']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/addresses
+  response:
+    body: {string: !!python/unicode '{"entries": [{"email": "user@example.com", "http_etag":
+        "\"52ace72a40745c0e003216ad8fbeb62bbf38e072\"", "original_email": "user@example.com",
+        "registered_on": "2005-08-01T07:49:23", "self_link": "http://localhost:9001/3.0/addresses/user@example.com",
+        "user": "http://localhost:9001/3.0/users/1", "verified_on": "2005-08-01T07:49:23"}],
+        "http_etag": "\"9580a3b8be6093d25a53e0656b32438452dabdbd\"", "start": 0, "total_size":
+        1}'}
+    headers:
+      content-length: ['425']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/users/1/addresses
+  response:
+    body: {string: !!python/unicode '{"entries": [{"email": "user@example.com", "http_etag":
+        "\"52ace72a40745c0e003216ad8fbeb62bbf38e072\"", "original_email": "user@example.com",
+        "registered_on": "2005-08-01T07:49:23", "self_link": "http://localhost:9001/3.0/addresses/user@example.com",
+        "user": "http://localhost:9001/3.0/users/1", "verified_on": "2005-08-01T07:49:23"}],
+        "http_etag": "\"9580a3b8be6093d25a53e0656b32438452dabdbd\"", "start": 0, "total_size":
+        1}'}
+    headers:
+      content-length: ['425']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: subscriber=user%40example.com
+    headers:
+      accept-encoding: ['gzip, deflate']
+      !!python/unicode content-type: [!!python/unicode application/x-www-form-urlencoded]
+    method: !!python/unicode POST
+    uri: http://localhost:9001/3.0/members/find
+  response:
+    body: {string: !!python/unicode '{"entries": [{"address": "http://localhost:9001/3.0/addresses/user@example.com",
+        "delivery_mode": "regular", "email": "user@example.com", "http_etag": "\"daa2142986cd1722628e6cdc494b6649d7e635f4\"",
+        "list_id": "foo.example.com", "member_id": 1, "moderation_action": "defer",
+        "role": "member", "self_link": "http://localhost:9001/3.0/members/1", "user":
+        "http://localhost:9001/3.0/users/1"}], "http_etag": "\"507c947b2e96fe6b2037a446f6d9897e0707b684\"",
+        "start": 0, "total_size": 1}'}
+    headers:
+      content-length: ['481']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+- request:
+    body: null
+    headers:
+      accept-encoding: ['gzip, deflate']
+    method: !!python/unicode GET
+    uri: http://localhost:9001/3.0/members/1/preferences
+  response:
+    body: {string: !!python/unicode '{"http_etag": "\"4747934e4e9b7e99c3faf1c663491719cbfe2dd0\"",
+        "self_link": "http://localhost:9001/3.0/members/1/preferences"}'}
+    headers:
+      content-length: ['125']
+      content-type: [application/json; charset=utf-8]
+    status: {code: 200, message: OK}
+version: 1
diff --git a/src/postorius/tests/mailman_api_tests/test_user.py b/src/postorius/tests/mailman_api_tests/test_user.py
index a40d973..3adf81d 100644
--- a/src/postorius/tests/mailman_api_tests/test_user.py
+++ b/src/postorius/tests/mailman_api_tests/test_user.py
@@ -25,6 +25,7 @@
 from django.contrib.auth.models import User
 from django.core.urlresolvers import reverse
 from django.test import TestCase
+from mock import patch
 from six.moves.urllib_parse import quote
 
 from postorius.models import MailmanUser
@@ -78,3 +79,47 @@
         self.assertEqual(len(response.context["zipped_data"]), 3)
         #self.assertEqual(
         #    response.context["formset"].initial['archive_policy'], 'public')
+
+    @MM_VCR.use_cassette('mailman_user_none_prefs.yaml')
+    def test_preferences_none(self):
+        # Mailman does not accept None values for boolean preferences. When
+        # those preferences are unset, they must be excluded from the POST
+        # data.
+        self.client.login(username='user', password='testpass')
+        self.foo_list.subscribe(self.user.email,
+            pre_verified=True, pre_confirmed=True, pre_approved=True)
+        prefs_with_none = (
+            'receive_own_postings', 'acknowledge_posts',
+            'hide_address', 'receive_list_copy',
+            )
+        # Prepare a Preferences subclass that will check the POST data 
+        import mailmanclient._client
+        class TestingPrefs(mailmanclient._client.Preferences):
+            testcase = self
+            def save(self):
+                for pref in prefs_with_none:
+                    self.testcase.assertNotIn(pref, self._changed_rest_data)
+        # Now check the relevant URLs
+        with patch('mailmanclient._client.Preferences') as pref_class:
+            pref_class.side_effect = TestingPrefs
+            # Simple forms
+            for url in (
+                    reverse('user_mailmansettings'),
+                    reverse('user_list_options', args=[self.foo_list.list_id]),
+                    ):
+                response = self.client.post(url,
+                    dict((pref, None) for pref in prefs_with_none))
+                self.assertEqual(response.status_code, 302)
+            # Formsets
+            for url in ('user_address_preferences', 'user_subscription_preferences'):
+                url = reverse(url)
+                post_data = dict(
+                    ('form-0-%s' % pref, None)
+                    for pref in prefs_with_none)
+                post_data.update({
+                    'form-TOTAL_FORMS': '1',
+                    'form-INITIAL_FORMS': '0',
+                    'form-MAX_NUM_FORMS': ''
+                })
+                response = self.client.post(url, post_data)
+                self.assertEqual(response.status_code, 302)
diff --git a/src/postorius/views/user.py b/src/postorius/views/user.py
index 6fcad66..0761ae2 100644
--- a/src/postorius/views/user.py
+++ b/src/postorius/views/user.py
@@ -47,12 +47,15 @@
     def post(self, request):
         try:
             mm_user = MailmanUser.objects.get(address=request.user.email)
-            global_preferences_form = UserPreferences(request.POST)
-            if global_preferences_form.is_valid():
+            form = UserPreferences(request.POST)
+            if form.is_valid():
                 preferences = mm_user.preferences
-                for key in global_preferences_form.fields.keys():
-                    preferences[
-                        key] = global_preferences_form.cleaned_data[key]
+                for key in form.fields.keys():
+                    if form.cleaned_data[key] is not None:
+                        # None: nothing set yet. Remember to remove this test
+                        # when Mailman accepts None as a "reset to default"
+                        # value.
+                        preferences[key] = form.cleaned_data[key]
                 preferences.save()
                 messages.success(request, _('Your preferences have been updated.'))
             else:
@@ -87,7 +90,11 @@
                 for form, address in zip(formset.forms, mm_user.addresses):
                     preferences = address.preferences
                     for key in form.fields.keys():
-                        preferences[key] = form.cleaned_data[key]
+                        if form.cleaned_data[key] is not None:
+                            # None: nothing set yet. Remember to remove this test
+                            # when Mailman accepts None as a "reset to default"
+                            # value.
+                            preferences[key] = form.cleaned_data[key]
                     preferences.save()
                 messages.success(request, _('Your preferences have been updated.'))
             else:
@@ -135,17 +142,23 @@
         form = UserPreferences(request.POST)
         if form.is_valid():
             for key in form.cleaned_data.keys():
-                preferences[key] = form.cleaned_data[key]
+                if form.cleaned_data[key] is not None:
+                    # None: nothing set yet. Remember to remove this test
+                    # when Mailman accepts None as a "reset to default"
+                    # value.
+                    preferences[key] = form.cleaned_data[key]
             preferences.save()
             messages.success(request, _('Your preferences have been updated.'))
+            return redirect("user_list_options", list_id)
         else:
             messages.error(request, _('Something went wrong.'))
     else:
         form = UserPreferences(initial=subscription.preferences)
     user_emails = [request.user.email] + request.user.other_emails
     subscription_form = ChangeSubscriptionForm(user_emails, initial={'email': subscription.email})
-    return render_to_response('postorius/user/list_options.html',
-            {'form': form, 'list': mlist, 'change_subscription_form': subscription_form}, context_instance=RequestContext(request))
+    return render(request, 'postorius/user/list_options.html',
+            {'form': form, 'list': mlist,
+             'change_subscription_form': subscription_form})
 
 
 class UserSubscriptionPreferencesView(MailmanUserView):
@@ -161,7 +174,11 @@
                 for form, subscription in zip(formset.forms, subscriptions):
                     preferences = subscription.preferences
                     for key in form.cleaned_data.keys():
-                        preferences[key] = form.cleaned_data[key]
+                        if form.cleaned_data[key] is not None:
+                            # None: nothing set yet. Remember to remove this test
+                            # when Mailman accepts None as a "reset to default"
+                            # value.
+                            preferences[key] = form.cleaned_data[key]
                     preferences.save()
                 messages.success(request, _('Your preferences have been updated.'))
             else: