diff --git a/db/migrate/20200912190210_update_weight_calculators.rb b/db/migrate/20200912190210_update_weight_calculators.rb
index bf027fd257..cdd8605468 100644
--- a/db/migrate/20200912190210_update_weight_calculators.rb
+++ b/db/migrate/20200912190210_update_weight_calculators.rb
@@ -4,6 +4,7 @@ class UpdateWeightCalculators < ActiveRecord::Migration
       calculator.preferred_unit_from_list = 'kg'
       calculator.preferred_per_unit = calculator.preferred_per_kg
       calculator.preferences.delete(:preferred_per_kg)
+      Rails.cache.delete(calculator.preference_cache_key("preferred_per_kg"))
       calculator.save
     }
   end