diff --git a/luncho/blueprints/users.py b/luncho/blueprints/users.py
index aab6410..9b2b8c4 100644
--- a/luncho/blueprints/users.py
+++ b/luncho/blueprints/users.py
@@ -6,13 +6,13 @@
 from flask import Blueprint
 from flask import request
 from flask import jsonify
-# from flask import current_app
 
-# from pony.orm import commit
+from sqlalchemy.exc import IntegrityError
 
 from luncho.helpers import ForceJSON
 
 from luncho.server import User
+from luncho.server import db
 
 users = Blueprint('users', __name__)
 
@@ -23,14 +23,19 @@ def create_user():
     """Create a new user. Request must be:
     { "username": "username", "full_name": "Full Name", "password": "hash" }"""
     json = request.get_json(force=True)
-    # new_user = User(username=json['username'],
-    #                 fullname=json['full_name'],
-    #                 passhash=json['password'],
-    #                 validated=False)
-    User(username=json['username'],
-         fullname=json['full_name'],
-         passhash=json['password'],
-         validated=False)
-    # commit()
-
-    return jsonify(status='OK')
+
+    try:
+        new_user = User(username=json['username'],
+                        fullname=json['full_name'],
+                        passhash=json['password'],
+                        validated=False)
+
+        db.session.add(new_user)
+        db.session.commit()
+
+        return jsonify(status='OK')
+    except IntegrityError:
+        resp = jsonify(status='ERROR',
+                       error='username already exists')
+        resp.status_code = 409
+        return resp
diff --git a/luncho/helpers.py b/luncho/helpers.py
index 2b9cca9..adc3ee6 100644
--- a/luncho/helpers.py
+++ b/luncho/helpers.py
@@ -18,8 +18,10 @@ class ForceJSON(object):
         def check_json(*args, **kwargs):
             json = request.get_json(force=True, silent=True)
             if not json:
-                return jsonify(status='ERROR',
-                               error='Request MUST be in JSON format'), 400
+                resp = jsonify(status='ERROR',
+                               error='Request MUST be in JSON format')
+                resp.status_code = 400
+                return resp
 
             # now we have the JSON, let's check if all the fields are here.
             missing = []
@@ -30,8 +32,10 @@ class ForceJSON(object):
             if missing:
                 fields = ', '.join(missing)
                 error = 'Missing fields: {fields}'.format(fields=fields)
-                return jsonify(status='ERROR',
+                resp = jsonify(status='ERROR',
                                error=error)
+                resp.status_code = 400
+                return resp
 
             return func(*args, **kwargs)
         return check_json
diff --git a/tests/users_tests.py b/tests/users_tests.py
index 0873644..36396bc 100644
--- a/tests/users_tests.py
+++ b/tests/users_tests.py
@@ -15,21 +15,64 @@ class TestUsers(unittest.TestCase):
         server.app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite://'
         server.app.config['TESTING'] = True
 
-        print server.app.config['SQLALCHEMY_DATABASE_URI']
         self.app = server.app.test_client()
+        server.db.create_all()
 
-    # def tearDown(self):
-    #     os.unlink(server.app.config['SQLITE_FILENAME'])
+    def tearDown(self):
+        server.db.drop_all(bind=None)
 
     def test_create_user(self):
+        """Simple user creation."""
         request = {'username': 'username',
                    'full_name': 'full name',
                    'password': 'hash'}
         rv = self.app.put('/user/',
                           data=json.dumps(request),
                           content_type='application/json')
+
         self.assertEqual(rv.status_code, 200)
         self.assertEqual(json.loads(rv.data), {'status': 'OK'})
 
+    def test_duplicate_user(self):
+        """Check the status for trying to create a user that it is already
+        in the database."""
+        self.test_create_user()     # create the first user
+
+        # now duplicate
+        request = {'username': 'username',
+                   'full_name': 'full name',
+                   'password': 'hash'}
+        rv = self.app.put('/user/',
+                          data=json.dumps(request),
+                          content_type='application/json')
+
+        expected = {"status": "ERROR",
+                    "error": "username already exists"}
+
+        self.assertEqual(rv.status_code, 409)
+        self.assertEqual(json.loads(rv.data), expected)
+
+    def test_no_json(self):
+        """Check the status when doing a request that it's not JSON."""
+        rv = self.app.put('/user/',
+                          data='',
+                          content_type='text/html')
+
+        expected = {"error": "Request MUST be in JSON format",
+                    "status": "ERROR"}
+        self.assertEqual(rv.status_code, 400)
+        self.assertEqual(json.loads(rv.data), expected)
+
+    def test_missing_fields(self):
+        request = {'password': 'hash'}
+        rv = self.app.put('/user/',
+                          data=json.dumps(request),
+                          content_type='application/json')
+
+        resp = {'error': 'Missing fields: username, full_name',
+                'status': 'ERROR'}
+        self.assertEqual(rv.status_code, 400)
+        self.assertEqual(json.loads(rv.data), resp)
+
 if __name__ == '__main__':
     unittest.main()