diff --git a/app/models/derived_variables/sales_log_variables.rb b/app/models/derived_variables/sales_log_variables.rb
index 3d837a6bf..36311ff22 100644
--- a/app/models/derived_variables/sales_log_variables.rb
+++ b/app/models/derived_variables/sales_log_variables.rb
@@ -168,7 +168,7 @@ private
     (start_index..6).each do |idx|
       if age_under_16?(idx)
         self["ecstat#{idx}"] = 9
-      elsif self["ecstat#{idx}"] == 9 && (self["age#{idx}_known"]).zero?
+      elsif self["ecstat#{idx}"] == 9 && age_known?(idx) == false
         self["ecstat#{idx}"] = nil
       end
     end