diff --git a/ceilometer/api/v1/app.py b/ceilometer/api/v1/app.py
index 76d64892..0ff6edfd 100644
--- a/ceilometer/api/v1/app.py
+++ b/ceilometer/api/v1/app.py
@@ -18,7 +18,6 @@
 """Set up the API server application instance."""
 
 import flask
-import flask.helpers
 from oslo.config import cfg
 
 from ceilometer.api import acl
@@ -26,10 +25,11 @@ from ceilometer.api.v1 import blueprint as v1_blueprint
 from ceilometer.openstack.common import jsonutils
 from ceilometer import storage
 
-# Replace the json module used by flask with the one from
-# openstack.common so we can take advantage of the fact that it knows
-# how to serialize more complex objects.
-flask.helpers.json = jsonutils
+
+class JSONEncoder(flask.json.JSONEncoder):
+    @staticmethod
+    def default(o):
+        return jsonutils.to_primitive(o)
 
 
 def make_app(conf, enable_acl=True, attach_storage=True,
@@ -37,6 +37,8 @@ def make_app(conf, enable_acl=True, attach_storage=True,
     app = flask.Flask('ceilometer.api')
     app.register_blueprint(v1_blueprint.blueprint, url_prefix='/v1')
 
+    app.json_encoder = JSONEncoder
+
     try:
         with open(sources_file, "r") as f:
             sources = jsonutils.load(f)
diff --git a/requirements.txt b/requirements.txt
index c08e2d2f..6a3edec5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,7 +10,7 @@ netaddr
 pymongo>=2.4
 eventlet>=0.13.0
 anyjson>=0.3.3
-Flask==0.9
+Flask>=0.10,<1.0
 pecan>=0.2.0
 stevedore>=0.10
 msgpack-python