diff --git a/activesupport/lib/active_support/core_ext/hash/except.rb b/activesupport/lib/active_support/core_ext/hash/except.rb
index f26d01553d..949976d741 100644
--- a/activesupport/lib/active_support/core_ext/hash/except.rb
+++ b/activesupport/lib/active_support/core_ext/hash/except.rb
@@ -10,7 +10,7 @@ module ActiveSupport #:nodoc:
       module Except
         # Returns a new hash without the given keys.
         def except(*keys)
-          clone.except!(*keys)
+          dup.except!(*keys)
         end
 
         # Replaces the hash without the given keys.
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index 7a414e946f..44d48e7577 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -341,6 +341,20 @@ class HashExtTest < Test::Unit::TestCase
     assert_equal expected, original.except!(:c)
     assert_equal expected, original
   end
+
+  def test_except_with_original_frozen
+    original = { :a => 'x', :b => 'y' }
+    original.freeze
+    assert_nothing_raised { original.except(:a) }
+  end
+
+  uses_mocha 'except with expectation' do
+    def test_except_with_mocha_expectation_on_original
+      original = { :a => 'x', :b => 'y' }
+      original.expects(:delete).never
+      original.except(:a)
+    end
+  end
 end
 
 class IWriteMyOwnXML