diff --git a/app/models/spree/shipping_method_decorator.rb b/app/models/spree/shipping_method_decorator.rb
index bd2a16af12..dd4c7d71de 100644
--- a/app/models/spree/shipping_method_decorator.rb
+++ b/app/models/spree/shipping_method_decorator.rb
@@ -42,6 +42,14 @@ Spree::ShippingMethod.class_eval do
     ]
   end
 
+  # This method is overriden so that we can remove the restriction added in Spree
+  #   Spree restricts shipping method calculators to the ones that inherit from Spree::Shipping::ShippingCalculator
+  #   Spree::Shipping::ShippingCalculator makes sure that calculators are able to handle packages and not orders as input
+  #   This is not necessary in OFN because calculators in OFN are already customized to work with different types of input
+  def self.calculators
+    spree_calculators.send model_name_without_spree_namespace
+  end
+
   def has_distributor?(distributor)
     self.distributors.include?(distributor)
   end
diff --git a/config/application.rb b/config/application.rb
index f80c91aee1..de267a8956 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -55,7 +55,15 @@ module Openfoodnetwork
 
     # Register Spree calculators
     initializer 'spree.register.calculators' do |app|
-      app.config.spree.calculators.shipping_methods << Calculator::Weight
+      app.config.spree.calculators.shipping_methods = [
+        Spree::Calculator::FlatPercentItemTotal,
+        Spree::Calculator::FlatRate,
+        Spree::Calculator::FlexiRate,
+        Spree::Calculator::PerItem,
+        Spree::Calculator::PriceSack,
+        Calculator::Weight
+      ]
+
       app.config.spree.calculators.add_class('enterprise_fees')
       config.spree.calculators.enterprise_fees = [
         Calculator::FlatPercentPerItem,
diff --git a/db/seeds.rb b/db/seeds.rb
index 9f0868cb6b..d1ae7f4a3d 100644
--- a/db/seeds.rb
+++ b/db/seeds.rb
@@ -51,4 +51,4 @@ end
 spree_user = Spree::User.first
 spree_user && spree_user.confirm!
 
-DefaultStockLocation.create!
+DefaultStockLocation.find_or_create
diff --git a/spec/serializers/api/shipping_method_serializer_spec.rb b/spec/serializers/api/shipping_method_serializer_spec.rb
new file mode 100644
index 0000000000..7ee9cb4d53
--- /dev/null
+++ b/spec/serializers/api/shipping_method_serializer_spec.rb
@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+describe Api::ShippingMethodSerializer do
+  let(:shipping_method) { create(:shipping_method) }
+
+  it "serializes a test shipping_method" do
+    serializer = Api::ShippingMethodSerializer.new shipping_method
+
+    expect(serializer.to_json).to match(shipping_method.name)
+  end
+
+  it "can serialize all configured shipping method calculators" do
+    Rails.application.config.spree.calculators.shipping_methods.each do |calculator|
+      shipping_method.calculator = calculator.new
+      serializer = Api::ShippingMethodSerializer.new shipping_method
+      allow(serializer).to receive(:options).and_return(current_order: create(:order))
+
+      expect(serializer.price).to eq(0.0)
+    end
+  end
+end