diff --git a/.travis.yml b/.travis.yml
index 05308be..e934991 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,7 @@ sudo: false
 cache: pip
 language: python
 python: 3.6
+dist: xenial
 
 env:
     - TOX_ENV=pypy-django11
diff --git a/django_statsd/middleware.py b/django_statsd/middleware.py
index c038703..87a370c 100644
--- a/django_statsd/middleware.py
+++ b/django_statsd/middleware.py
@@ -125,7 +125,7 @@ def __call__(self, key):
 class StatsdMiddleware(deprecation.MiddlewareMixin):
     scope = threading.local()
 
-    def __init__(self, get_response):
+    def __init__(self, get_response=None):
         deprecation.MiddlewareMixin.__init__(self, get_response)
         self.scope.timings = None
         self.scope.counter = None