diff --git a/app/controllers/spree/products_controller_decorator.rb b/app/controllers/spree/products_controller_decorator.rb
index a231a1ce..bf206e37 100644
--- a/app/controllers/spree/products_controller_decorator.rb
+++ b/app/controllers/spree/products_controller_decorator.rb
@@ -1,5 +1,7 @@
-Spree::ProductsController.class_eval do
-  helper Spree::ReviewsHelper
+module Spree::ProductsControllerDecorator
+  def self.prepended(base)
+    base.helper Spree::ReviewsHelper
+  end
 
   reviews_fields = [:avg_rating, :reviews_count]
   reviews_fields.each { |attrib| Spree::PermittedAttributes.product_attributes << attrib }
@@ -8,3 +10,5 @@
     reviews_fields.each { |attrib| class_variable_set(:@@product_attributes, class_variable_get(:@@product_attributes).push(attrib)) }
   end
 end
+
+::Spree::ProductsController.prepend(Spree::ProductsControllerDecorator)
diff --git a/app/models/spree/product_decorator.rb b/app/models/spree/product_decorator.rb
index c7a7083f..92f4a860 100644
--- a/app/models/spree/product_decorator.rb
+++ b/app/models/spree/product_decorator.rb
@@ -1,6 +1,8 @@
 # Add access to reviews/ratings to the product model
-Spree::Product.class_eval do
-  has_many :reviews
+module Spree::ProductDecorator
+  def self.prepended(base)
+    base.has_many :reviews
+  end
 
   def stars
     avg_rating.try(:round) || 0
@@ -16,3 +18,5 @@ def recalculate_rating
     save
   end
 end
+
+::Spree::Product.prepend(Spree::ProductDecorator)
diff --git a/spree_reviews.gemspec b/spree_reviews.gemspec
index 9dd61085..19d36756 100644
--- a/spree_reviews.gemspec
+++ b/spree_reviews.gemspec
@@ -21,7 +21,7 @@ Gem::Specification.new do |s|
   s.require_path = 'lib'
   s.requirements << 'none'
 
-  spree_version = '>= 3.1.0', '< 4.0'
+  spree_version = '>= 3.1.0', '< 5.0'
   s.add_runtime_dependency 'spree_core', spree_version
   s.add_runtime_dependency 'spree_auth_devise', spree_version
   s.add_runtime_dependency 'spree_extension'