diff --git a/app/models/lab_tech/result.rb b/app/models/lab_tech/result.rb
index 1696a10..9a258ea 100644
--- a/app/models/lab_tech/result.rb
+++ b/app/models/lab_tech/result.rb
@@ -115,7 +115,7 @@ def record_observation(scientist_observation, attrs = {})
     def record_simple_stats(scientist_result)
       cont, cands = scientist_result.control, scientist_result.candidates
 
-      self.equivalent = cands.all? { |cand| cont.equivalent_to?(cand, &experiment.comparator) }
+      self.equivalent = cands.all? { |cand| cont.equivalent_to?(cand, comparator = experiment.comparator) }
 
       raised = ->(scientist_observation) { scientist_observation.exception.present? }
       self.raised_error = !raised.(cont) && cands.any?(&raised)