diff --git a/lib/aasm.rb b/lib/aasm.rb
index e90e9b5..b5a91ca 100644
--- a/lib/aasm.rb
+++ b/lib/aasm.rb
@@ -22,7 +22,7 @@ module AASM
 
   module ClassMethods
     def inherited(klass)
-      AASM::StateMachine[klass] = AASM::StateMachine[self].dup
+      AASM::StateMachine[klass] = AASM::StateMachine[self].clone
       super
     end
 
diff --git a/lib/state_machine.rb b/lib/state_machine.rb
index cd98bf0..672aef5 100644
--- a/lib/state_machine.rb
+++ b/lib/state_machine.rb
@@ -22,6 +22,12 @@ module AASM
       @config = OpenStruct.new
     end
 
+    def clone
+      klone = super
+      klone.states = states.clone
+      klone
+    end
+
     def create_state(name, options)
       @states << AASM::SupportingClasses::State.new(name, options) unless @states.include?(name)
     end
diff --git a/spec/unit/aasm_spec.rb b/spec/unit/aasm_spec.rb
index 14ac92e..30cfe87 100644
--- a/spec/unit/aasm_spec.rb
+++ b/spec/unit/aasm_spec.rb
@@ -70,12 +70,21 @@ describe AASM, '- class level definitions' do
 end
 
 
-describe AASM, '- when included' do
-  it 'should invoke the original inherited callback when subclassed' do
-    parent = Class.new
-    parent.should_receive(:inherited)
-    parent.send(:include, AASM)
-    child = Class.new(parent)
+describe AASM, '- subclassing' do
+  before(:each) do
+    @parent = Class.new do
+      include AASM
+    end
+  end
+
+  it 'should invoke the original inherited callback' do
+    @parent.should_receive(:inherited)
+    Class.new(@parent)
+  end
+
+  it 'should have a unique states hash' do
+    child = Class.new(@parent)
+    child.aasm_states.equal?(@parent.aasm_states).should be_false
   end
 end