diff --git a/app/models/spree/stock/availability_validator.rb b/app/models/spree/stock/availability_validator.rb
index 1ca304e8d0..6c9516cd08 100644
--- a/app/models/spree/stock/availability_validator.rb
+++ b/app/models/spree/stock/availability_validator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Spree
   module Stock
     class AvailabilityValidator < ActiveModel::Validator