diff --git a/app/controllers/spree/admin/prototypes_controller.rb b/app/controllers/spree/admin/prototypes_controller.rb
index 63b2849..8075d03 100644
--- a/app/controllers/spree/admin/prototypes_controller.rb
+++ b/app/controllers/spree/admin/prototypes_controller.rb
@@ -2,26 +2,31 @@
 
 module Spree
   module Admin
-    class PrototypesController < ResourceController
-      def show
-        if request.xhr?
-          render layout: false
-        else
-          redirect_to admin_prototypes_path
+    if defined? ::Spree::Backend
+      class PrototypesController < ResourceController
+        def show
+          if request.xhr?
+            render layout: false
+          else
+            redirect_to admin_prototypes_path
+          end
         end
-      end
 
-      def available
-        @prototypes = Prototype.order('name asc')
-        respond_with(@prototypes) do |format|
-          format.html { render layout: !request.xhr? }
-          format.js
+        def available
+          @prototypes = Prototype.order('name asc')
+          respond_with(@prototypes) do |format|
+            format.html { render layout: !request.xhr? }
+            format.js
+          end
         end
-      end
 
-      def select
-        @prototype ||= Prototype.find(params[:id])
-        @prototype_properties = @prototype.properties
+        def select
+          @prototype ||= Prototype.find(params[:id])
+          @prototype_properties = @prototype.properties
+        end
+      end
+    else
+      class PrototypesController
       end
     end
   end
diff --git a/config/initializers/spree.rb b/config/initializers/spree.rb
index f4eb050..dd1ca54 100644
--- a/config/initializers/spree.rb
+++ b/config/initializers/spree.rb
@@ -1,18 +1,20 @@
 Rails.application.config.to_prepare do
   Spree::PermittedAttributes.product_attributes << :prototype_id
-  Spree::Backend::Config.configure do |config|
-    product_tab = config.menu_items.detect { |menu_item|
-      menu_item.label == :products
-    }
-    if product_tab.respond_to?(:children)
-      product_tab.children << Spree::BackendConfiguration::MenuItem.new(
-        condition: -> { can?(:admin, Spree::Prototype) },
-        url: :admin_prototypes_path,
-        label: :prototypes,
-        match_path: '/prototypes'
-      )
-    else
-      product_tab.sections << :prototypes
+  if defined?(Spree::Backend)
+    Spree::Backend::Config.configure do |config|
+      product_tab = config.menu_items.detect { |menu_item|
+        menu_item.label == :products
+      }
+      if product_tab.respond_to?(:children)
+        product_tab.children << Spree::BackendConfiguration::MenuItem.new(
+          condition: -> { can?(:admin, Spree::Prototype) },
+          url: :admin_prototypes_path,
+          label: :prototypes,
+          match_path: '/prototypes'
+        )
+      else
+        product_tab.sections << :prototypes
+      end
     end
   end
 end
diff --git a/lib/backend/controllers/spree/admin/products_controller_decorator.rb b/lib/backend/controllers/spree/admin/products_controller_decorator.rb
index 589bdbc..2199e26 100644
--- a/lib/backend/controllers/spree/admin/products_controller_decorator.rb
+++ b/lib/backend/controllers/spree/admin/products_controller_decorator.rb
@@ -19,7 +19,7 @@ def load_prototype
         @prototype = Spree::Prototype.find(params[resource][:prototype_id])
       end
 
-      ::Spree::Admin::ProductsController.prepend self
+      ::Spree::Admin::ProductsController.prepend self if defined? ::Spree::Admin::ProductsController
     end
   end
 end
diff --git a/solidus_prototypes.gemspec b/solidus_prototypes.gemspec
index 324ea23..da80a47 100644
--- a/solidus_prototypes.gemspec
+++ b/solidus_prototypes.gemspec
@@ -10,7 +10,7 @@ Gem::Specification.new do |s|
   s.description = "Breaking out prototypes from solidus"
   s.license = "BSD-3-Clause"
 
-  s.required_ruby_version = [">= 3.0", "< 4"]
+  s.required_ruby_version = Gem::Requirement.new('>= 3.0')
 
   s.author = "Graeme Nathan"
   s.email = "graeme@stembolt.com"
@@ -34,5 +34,8 @@ Gem::Specification.new do |s|
   s.add_dependency "solidus_core", [">= 3.2.0", "< 5"]
   s.add_dependency "solidus_support", "~> 0.4"
 
-  s.add_development_dependency "solidus_dev_support"
+  s.add_development_dependency 'rubocop', '~> 1.0'
+  s.add_development_dependency 'rubocop-performance', '~> 1.5'
+  s.add_development_dependency 'rubocop-rails', '~> 2.3'
+  s.add_development_dependency 'rubocop-rspec', '~> 2.0'
 end