diff --git a/lib/aasm.rb b/lib/aasm.rb
index 3cc40ff..e32a713 100644
--- a/lib/aasm.rb
+++ b/lib/aasm.rb
@@ -1,6 +1,7 @@
 require 'ostruct'
 
 require File.join(File.dirname(__FILE__), 'aasm', 'version')
+require File.join(File.dirname(__FILE__), 'aasm', 'errors')
 require File.join(File.dirname(__FILE__), 'aasm', 'base')
 require File.join(File.dirname(__FILE__), 'aasm', 'supporting_classes', 'state_transition')
 require File.join(File.dirname(__FILE__), 'aasm', 'supporting_classes', 'event')
diff --git a/lib/aasm/aasm.rb b/lib/aasm/aasm.rb
index 186517d..5b85ce7 100644
--- a/lib/aasm/aasm.rb
+++ b/lib/aasm/aasm.rb
@@ -1,9 +1,4 @@
 module AASM
-  class InvalidTransition < RuntimeError
-  end
-
-  class UndefinedState < RuntimeError
-  end
 
   def self.included(base) #:nodoc:
     base.extend AASM::ClassMethods
diff --git a/lib/aasm/errors.rb b/lib/aasm/errors.rb
new file mode 100644
index 0000000..2b629d6
--- /dev/null
+++ b/lib/aasm/errors.rb
@@ -0,0 +1,4 @@
+module AASM
+  class InvalidTransition < RuntimeError; end
+  class UndefinedState < RuntimeError; end
+end