diff --git a/app/models/derived_variables/sales_log_variables.rb b/app/models/derived_variables/sales_log_variables.rb
index 76811740c..3f4d61114 100644
--- a/app/models/derived_variables/sales_log_variables.rb
+++ b/app/models/derived_variables/sales_log_variables.rb
@@ -120,7 +120,7 @@ private
         mortgageused: 3,
       },
       derived_values: {
-        mortgage: 0,
+        mortgage: nil,
       },
     },
   ].freeze