diff --git a/promotions/app/models/solidus_promotions/promotion.rb b/promotions/app/models/solidus_promotions/promotion.rb
index e36015facac..7eacbbf61af 100644
--- a/promotions/app/models/solidus_promotions/promotion.rb
+++ b/promotions/app/models/solidus_promotions/promotion.rb
@@ -9,7 +9,7 @@ class Promotion < Spree::Base
     belongs_to :original_promotion, class_name: "Spree::Promotion", optional: true
     has_many :benefits, class_name: "SolidusPromotions::Benefit", dependent: :destroy
     has_many :conditions, through: :benefits
-    has_many :codes, class_name: "SolidusPromotions::PromotionCode", dependent: :destroy
+    has_many :codes, class_name: "SolidusPromotions::PromotionCode", dependent: :destroy, inverse_of: :promotion
     has_many :code_batches, class_name: "SolidusPromotions::PromotionCodeBatch", dependent: :destroy
     has_many :order_promotions, class_name: "SolidusPromotions::OrderPromotion", dependent: :destroy
 
diff --git a/promotions/lib/controllers/backend/solidus_promotions/admin/promotion_codes_controller.rb b/promotions/lib/controllers/backend/solidus_promotions/admin/promotion_codes_controller.rb
index ee23a457469..0310fc54ceb 100644
--- a/promotions/lib/controllers/backend/solidus_promotions/admin/promotion_codes_controller.rb
+++ b/promotions/lib/controllers/backend/solidus_promotions/admin/promotion_codes_controller.rb
@@ -48,6 +48,10 @@ def create
 
       private
 
+      def model_class
+        SolidusPromotions::PromotionCode
+      end
+
       def load_promotion
         @promotion = SolidusPromotions::Promotion
           .accessible_by(current_ability, :show)