diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 2f38e0c..565d6c4 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -195,4 +195,3 @@ Style/StringLiterals:
 Style/SymbolArray:
   Exclude:
     - 'lib/chrono_model/adapter.rb'
-    - 'lib/chrono_model/time_machine/timeline.rb'
diff --git a/lib/chrono_model/time_machine/timeline.rb b/lib/chrono_model/time_machine/timeline.rb
index 4f0acbe..d56a478 100644
--- a/lib/chrono_model/time_machine/timeline.rb
+++ b/lib/chrono_model/time_machine/timeline.rb
@@ -110,7 +110,7 @@ def quoted_history_fields
         @quoted_history_fields ||= begin
           validity = "#{connection.quote_table_name(table_name)}.#{connection.quote_column_name('validity')}"
 
-          [:lower, :upper].map! { |func| "#{func}(#{validity})" }
+          %w(lower upper).map! { |func| "#{func}(#{validity})" }
         end
       end
     end