diff --git a/activerecord/lib/active_record/relation/merger.rb b/activerecord/lib/active_record/relation/merger.rb
index 0b38666ce970001f1d21fb5b18e073c94fa7629c..cb971eb255e8c1ae405cee571e04556aee9b0487 100644
--- a/activerecord/lib/active_record/relation/merger.rb
+++ b/activerecord/lib/active_record/relation/merger.rb
@@ -148,11 +148,15 @@ def merge_single_values
         end
       end
 
+      CLAUSE_METHOD_NAMES = CLAUSE_METHODS.map do |name|
+        ["#{name}_clause", "#{name}_clause="]
+      end
+
       def merge_clauses
-        CLAUSE_METHODS.each do |name|
-          clause = relation.send("#{name}_clause")
-          other_clause = other.send("#{name}_clause")
-          relation.send("#{name}_clause=", clause.merge(other_clause))
+        CLAUSE_METHOD_NAMES.each do |(reader, writer)|
+          clause = relation.send(reader)
+          other_clause = other.send(reader)
+          relation.send(writer, clause.merge(other_clause))
         end
       end
     end