diff --git a/Changelog.md b/Changelog.md
index 40c3336f..c8c127b3 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,10 +1,11 @@
-# v0.5.11 2014-04-07
+# v0.5.11 2014-04-xx
 
 Changes:
 
 * Fix crash on while and until without body
 * Better require highjack based zombifier
 * Do not mutate nthref $1 to gvar $0
+* Use faster duplicate guarding hashing AST::Node intances
 
 # v0.5.10 2014-04-06
 
diff --git a/Gemfile b/Gemfile
index 39e6cb41..b9044199 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,6 +3,7 @@
 source 'https://rubygems.org'
 
 gem 'mutant', path: '.'
+gem 'morpher', git: 'https://github.com/mbj/morpher'
 
 gemspec name: 'mutant'
 
diff --git a/lib/mutant.rb b/lib/mutant.rb
index 02459f05..7360cd55 100644
--- a/lib/mutant.rb
+++ b/lib/mutant.rb
@@ -10,7 +10,6 @@ require 'equalizer'
 require 'digest/sha1'
 require 'inflecto'
 require 'parser'
-require 'parser_extensions'
 require 'parser/current'
 require 'unparser'
 require 'ice_nine'
diff --git a/lib/parser_extensions.rb b/lib/parser_extensions.rb
deleted file mode 100644
index 2c140a8c..00000000
--- a/lib/parser_extensions.rb
+++ /dev/null
@@ -1,36 +0,0 @@
-# Monkey patch to parser that needs to be pushed upstream
-module Parser
-  # AST namespace
-  module AST
-    # The AST nodes we use in mutant
-    class Node
-
-      # Return hash compatible with #eql?
-      #
-      # @return [Fixnum]
-      #
-      # @api private
-      def hash
-        @type.hash ^ @children.hash ^ self.class.hash
-      end
-
-      # Test if node is equal to anotheo
-      #
-      # @return [true]
-      #   if node represents the same code semantics locations are ignored
-      #
-      # @return [false]
-      #   otherwise
-      #
-      # @api private
-      #
-      def eql?(other)
-        other.kind_of?(self.class)
-        other.type.eql?(@type) && other.children.eql?(@children)
-      end
-
-    end # Node
-  end # AST
-end # Parser
-
-
diff --git a/mutant.gemspec b/mutant.gemspec
index bace8dd2..a1255c6f 100644
--- a/mutant.gemspec
+++ b/mutant.gemspec
@@ -24,6 +24,7 @@ Gem::Specification.new do |gem|
   gem.required_ruby_version = '>= 1.9.3'
 
   gem.add_runtime_dependency('parser',        '~> 2.1')
+  gem.add_runtime_dependency('ast',           '~> 2.0')
   gem.add_runtime_dependency('diff-lcs',      '~> 1.2')
   gem.add_runtime_dependency('morpher',       '~> 0.2.2')
   gem.add_runtime_dependency('procto',        '~> 0.0.2')