diff --git a/app/models/spree/product.rb b/app/models/spree/product.rb
index ba436551f8..bb42d78b43 100755
--- a/app/models/spree/product.rb
+++ b/app/models/spree/product.rb
@@ -90,7 +90,7 @@ module Spree
 
     validates :supplier, presence: true
     validates :primary_taxon, presence: true
-    validates :tax_category_id, presence: true, if: "Spree::Config.products_require_tax_category"
+    validates :tax_category_id, presence: true, if: proc { Spree::Config[:products_require_tax_category] }
 
     validates :variant_unit, presence: true
     validates :unit_value, presence: { if: ->(p) { %w(weight volume).include? p.variant_unit } }