diff --git a/activemodel/lib/active_model/state_machine.rb b/activemodel/lib/active_model/state_machine.rb
index bce90fd743..1172d31ea3 100644
--- a/activemodel/lib/active_model/state_machine.rb
+++ b/activemodel/lib/active_model/state_machine.rb
@@ -1,5 +1,10 @@
 module ActiveModel
   module StateMachine
+    autoload :Event, 'active_model/state_machine/event'
+    autoload :Machine, 'active_model/state_machine/machine'
+    autoload :State, 'active_model/state_machine/state'
+    autoload :StateTransition, 'active_model/state_machine/state_transition'
+
     class InvalidTransition < Exception
     end