diff --git a/django_mock_queries/asserts.py b/django_mock_queries/asserts.py
index e233c71..e131ba2 100644
--- a/django_mock_queries/asserts.py
+++ b/django_mock_queries/asserts.py
@@ -3,6 +3,8 @@
 
 from .constants import *
 
+SkipField = locate('rest_framework.fields.SkipField')
+
 
 class SerializerAssert:
     _obj = None
diff --git a/django_mock_queries/constants.py b/django_mock_queries/constants.py
index 2296191..2de7abd 100644
--- a/django_mock_queries/constants.py
+++ b/django_mock_queries/constants.py
@@ -47,4 +47,3 @@
 DjangoQuerySet = locate('django.db.models.QuerySet')
 ObjectDoesNotExist = locate('django.core.exceptions.ObjectDoesNotExist')
 MultipleObjectsReturned = locate('django.core.exceptions.MultipleObjectsReturned')
-SkipField = locate('rest_framework.fields.SkipField')
diff --git a/requirements/requirements-testing.txt b/requirements/requirements-testing.txt
index 05fe674..8d14f51 100644
--- a/requirements/requirements-testing.txt
+++ b/requirements/requirements-testing.txt
@@ -1,5 +1,6 @@
 -r requirements.txt
 
+flake8==2.5.4
 pytest==2.8.2
 pytest-cov==2.2.0
 pytest-flake8==0.2