diff --git a/lib/sequent/configuration.rb b/lib/sequent/configuration.rb
index 79e778d2..aa83f0c3 100644
--- a/lib/sequent/configuration.rb
+++ b/lib/sequent/configuration.rb
@@ -1,10 +1,17 @@
 # frozen_string_literal: true
 
+require_relative 'core/random_uuid_generator'
+require_relative 'core/base_command_handler'
+require_relative 'core/command'
 require_relative 'core/event_store'
+require_relative 'core/event_publisher'
+require_relative 'core/aggregate_snapshotter'
 require_relative 'core/command_service'
 require_relative 'core/transactions/no_transactions'
 require_relative 'core/aggregate_repository'
+require_relative 'core/middleware/chain'
 require_relative 'core/persistors/active_record_persistor'
+require_relative 'core/transactions/active_record_transaction_provider'
 require 'logger'
 
 module Sequent
diff --git a/lib/sequent/core/ext/ext.rb b/lib/sequent/core/ext/ext.rb
index 0ffe503d..882367c7 100644
--- a/lib/sequent/core/ext/ext.rb
+++ b/lib/sequent/core/ext/ext.rb
@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
+require 'bigdecimal'
+require 'date'
+
 class Symbol
   def self.deserialize_from_json(value)
     value.blank? ? nil : value.try(:to_sym)
diff --git a/lib/sequent/core/helpers/message_handler.rb b/lib/sequent/core/helpers/message_handler.rb
index 520ee7be..0708522b 100644
--- a/lib/sequent/core/helpers/message_handler.rb
+++ b/lib/sequent/core/helpers/message_handler.rb
@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
+require 'active_support'
+require 'active_support/core_ext/class/attribute'
+
 require_relative 'message_handler_option_registry'
 require_relative 'message_router'