diff --git a/orchestra/admin/utils.py b/orchestra/admin/utils.py
index 904df2f2..9c485d2a 100644
--- a/orchestra/admin/utils.py
+++ b/orchestra/admin/utils.py
@@ -94,7 +94,7 @@ def change_url(obj):
     if obj is not None:
         cls = type(obj)
         opts = obj._meta
-        if cls._deferred:
+        if cls is models.DEFERRED:
             opts = cls.__base__._meta
         view_name = 'admin:%s_%s_change' % (opts.app_label, opts.model_name)
         return reverse(view_name, args=(obj.pk,))
diff --git a/orchestra/api/options.py b/orchestra/api/options.py
index 0620d9c7..8b377564 100644
--- a/orchestra/api/options.py
+++ b/orchestra/api/options.py
@@ -59,7 +59,7 @@ class LogApiMixin(object):
 
 
 class LinkHeaderRouter(DefaultRouter):
-    def get_api_root_view(self):
+    def get_api_root_view(self, api_urls=None):
         """ returns the root view, with all the linked collections """
         APIRoot = import_class(settings.ORCHESTRA_API_ROOT_VIEW)
         APIRoot.router = self
diff --git a/orchestra/bin/orchestra-admin b/orchestra/bin/orchestra-admin
index b480490e..22a26e72 100755
--- a/orchestra/bin/orchestra-admin
+++ b/orchestra/bin/orchestra-admin
@@ -161,7 +161,7 @@ function install_requirements () {
             coverage \
             flake8 \
             django-debug-toolbar==1.3.0 \
-            django-nose==1.4 \
+            django-nose==1.4.4 \
             sqlparse \
             pyinotify \
             PyMySQL"
diff --git a/orchestra/contrib/bills/models.py b/orchestra/contrib/bills/models.py
index 5e2896a0..02f0b386 100644
--- a/orchestra/contrib/bills/models.py
+++ b/orchestra/contrib/bills/models.py
@@ -124,7 +124,7 @@ class Bill(models.Model):
     
     @classmethod
     def get_class_type(cls):
-        if cls._deferred:
+        if cls is models.DEFERRED:
             cls = cls.__base__
         return cls.__name__.upper()
     
@@ -227,7 +227,7 @@ class Bill(models.Model):
     
     def get_number(self):
         cls = type(self)
-        if cls._deferred:
+        if cls is models.DEFERRED:
             cls = cls.__base__
         bill_type = self.get_type()
         if bill_type == self.BILL:
diff --git a/orchestra/contrib/systemusers/apps.py b/orchestra/contrib/systemusers/apps.py
index 021d92d9..e0db6346 100644
--- a/orchestra/contrib/systemusers/apps.py
+++ b/orchestra/contrib/systemusers/apps.py
@@ -19,7 +19,7 @@ class SystemUsersConfig(AppConfig):
     
     def create_initial_systemuser(self, **kwargs):
         from .models import SystemUser
-        Account = SystemUser.account.field.related.model
+        Account = SystemUser.account.field.remote_field.model
         for account in Account.objects.filter(is_superuser=True, main_systemuser_id__isnull=True):
             systemuser = SystemUser.objects.create(username=account.username,
                 password=account.password, account=account)
diff --git a/orchestra/models/fields.py b/orchestra/models/fields.py
index 8d892762..44331180 100644
--- a/orchestra/models/fields.py
+++ b/orchestra/models/fields.py
@@ -51,7 +51,7 @@ class MultiSelectField(models.CharField):
     
     def validate(self, value, model_instance):
         if self.choices:
-            arr_choices = self.get_choices_selected(self.get_choices_default())
+            arr_choices = self.get_choices_selected(self.get_choices())
             for opt_select in value:
                 if (opt_select not in arr_choices):
                     msg = self.error_messages['invalid_choice'] % {'value': opt_select}
diff --git a/requirements.txt b/requirements.txt
index e53bb8f7..b4b0a0b7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,13 +1,13 @@
 Django==1.9.5
 django-fluent-dashboard==0.6.1
-django-admin-tools==0.7.2
+django-admin-tools==0.8.0
 django-extensions==1.7.4
 django-celery==3.1.17
 celery==3.1.23
 kombu==3.0.35
 billiard==3.3.0.23
 Markdown==2.4
-djangorestframework==3.3.2
+djangorestframework==3.4.7
 ecdsa==0.11
 Pygments==1.6
 django-filter==0.7