1 files changed, 4 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb b/activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb
index ad891f841e..e15d7b013f 100644
--- a/activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb
+++ b/activemodel/lib/active_model/type/helpers/accepts_multiparameter_time.rb
@@ -5,6 +5,10 @@ module ActiveModel
     module Helpers # :nodoc: all
       class AcceptsMultiparameterTime < Module
         def initialize(defaults: {})
+          define_method(:serialize) do |value|
+            super(cast(value))
+          end
+
           define_method(:cast) do |value|
             if value.is_a?(Hash)
               value_from_multiparameter_assignment(value)