diff --git a/activesupport/lib/active_support/duration.rb b/activesupport/lib/active_support/duration.rb
index 88897f811e..314c926ac0 100644
--- a/activesupport/lib/active_support/duration.rb
+++ b/activesupport/lib/active_support/duration.rb
@@ -373,7 +373,6 @@ module ActiveSupport
       return "0 seconds" if parts.empty?
 
       parts.
-        reduce(::Hash.new(0)) { |h, (l, r)| h[l] += r; h }.
         sort_by { |unit,  _ | PARTS.index(unit) }.
         map     { |unit, val| "#{val} #{val == 1 ? unit.to_s.chop : unit.to_s}" }.
         to_sentence(locale: ::I18n.default_locale)