diff --git a/app/controllers/api/coupons_controller.rb b/app/controllers/api/coupons_controller.rb
index 15d6b7957..fbdbef9ae 100644
--- a/app/controllers/api/coupons_controller.rb
+++ b/app/controllers/api/coupons_controller.rb
@@ -26,7 +26,7 @@ class API::CouponsController < API::ApiController
     else
       status = @coupon.status
       if status != 'active'
-        render json: {status: status}, status: :unauthorized
+        render json: {status: status}, status: :unprocessable_entity
       else
         render :validate, status: :ok, location: @coupon
       end
diff --git a/app/models/coupon.rb b/app/models/coupon.rb
index d9a9bc32a..eba7fe0a8 100644
--- a/app/models/coupon.rb
+++ b/app/models/coupon.rb
@@ -10,6 +10,7 @@ class Coupon < ActiveRecord::Base
   validates :code, uniqueness: true
   validates :percent_off, presence: true
   validates :percent_off, :inclusion => 0..100
+  validates :validity_per_user, presence: true
 
   def safe_destroy
     if self.invoices.size == 0
diff --git a/test/fixtures/coupons.yml b/test/fixtures/coupons.yml
index e2ba7a6b1..f5eb6d362 100644
--- a/test/fixtures/coupons.yml
+++ b/test/fixtures/coupons.yml
@@ -5,10 +5,9 @@ one:
   code: XMAS10
   percent_off: 10
   valid_until: 2015-12-31 23:59:59
-  max_usages: 0
-  usages: 1
+  max_usages: nil
   active: true
-  stp_coupon_id: a3OlfO4u
+  validity_per_user: once
 
 two:
   name: Summer discounts
@@ -16,6 +15,5 @@ two:
   percent_off: 15
   valid_until: <%= 1.month.from_now.utc.strftime('%Y-%m-%d %H:%M:%S.%9N Z') %>
   max_usages: 10
-  usages: 9
   active: true
-  stp_coupon_id: a42pm11w
+  validity_per_user: always
diff --git a/test/models/coupon_test.rb b/test/models/coupon_test.rb
index 69e2e5d69..4ccdc535e 100644
--- a/test/models/coupon_test.rb
+++ b/test/models/coupon_test.rb
@@ -2,7 +2,17 @@ require 'test_helper'
 
 class CouponTest < ActiveSupport::TestCase
   test 'coupon must have a valid percentage' do
-    c = Coupon.new({code: 'DISCOUNT', percent_off: 800})
+    c = Coupon.new({name: 'Amazing deal', code: 'DISCOUNT', percent_off: 200, validity_per_user: 'once'})
+    assert c.invalid?
+  end
+
+  test 'expired coupon must return the proper status' do
+    c = Coupon.find_by_code('XMAS10')
+    assert c.status == 'expired'
+  end
+
+  test 'two coupons cannot have the same code' do
+    c = Coupon.new({name: 'Summer deals', code: 'SUNNYFABLAB', percent_off: 15, validity_per_user: 'always'})
     assert c.invalid?
   end
 end