diff --git a/app/models/derived_variables/lettings_log_variables.rb b/app/models/derived_variables/lettings_log_variables.rb
index 861b99300..937dd7c2e 100644
--- a/app/models/derived_variables/lettings_log_variables.rb
+++ b/app/models/derived_variables/lettings_log_variables.rb
@@ -37,7 +37,7 @@ module DerivedVariables::LettingsLogVariables
   end
 
   def set_derived_fields!
-    clear_inapplicable_derived_values
+    clear_inapplicable_derived_values!
     set_encoded_derived_values!(DEPENDENCIES)
 
     if rsnvac.present?
@@ -130,7 +130,7 @@ private
     },
   ].freeze
 
-  def clear_inapplicable_derived_values
+  def clear_inapplicable_derived_values!
     reset_invalidated_derived_values!(DEPENDENCIES)
     if (startdate_changed? || renewal_changed?) && (renewal_was == 1 && startdate_was&.between?(Time.zone.local(2021, 4, 1), Time.zone.local(2022, 3, 31)))
       self.underoccupation_benefitcap = nil
diff --git a/spec/models/lettings_log_spec.rb b/spec/models/lettings_log_spec.rb
index ebd8303a6..5e661fe16 100644
--- a/spec/models/lettings_log_spec.rb
+++ b/spec/models/lettings_log_spec.rb
@@ -1574,7 +1574,6 @@ RSpec.describe LettingsLog do
         expect { lettings_log.update!(renewal: 0) }.to change(lettings_log, :rsnvac).from(14).to nil
       end
 
-      # should have extra tests for whether it is derived when voiddate, mrcdate etc set and reset
       it "derives vacdays as 0 if log is renewal" do
         expect { lettings_log.update!(renewal: 1) }.to change(lettings_log, :vacdays).to 0
       end