diff --git a/lib/mutant.rb b/lib/mutant.rb
index 1aedbeea..a80c89b9 100644
--- a/lib/mutant.rb
+++ b/lib/mutant.rb
@@ -12,6 +12,7 @@ require 'digest/sha1'
 require 'inflecto'
 require 'parser'
 require 'parser/current'
+require 'parser-node-list'
 require 'unparser'
 require 'ice_nine'
 require 'diff/lcs'
@@ -21,31 +22,6 @@ require 'anima'
 require 'concord'
 require 'rspec'
 
-# Monkeypatch on parser with a list of allowed nodes.
-# Will be pushed upstream once turning out to be correct.
-module Parser
-  module Meta
-    NODE_TYPES =
-      %w(
-        true false nil int float str dstr str
-        sym dsym xstr regopt regexp array splat
-        array pair kwsplat hash irange erange self
-        lvar ivar cvar gvar const defined? lvasgn
-        ivasgn cvasgn gvasgn casgn mlhs masgn op_asgn
-        op_asgn and_asgn ensure rescue arg_expr
-        or_asgn and_asgn or_asgn back_ref nth_ref
-        match_with_lvasgn match_current_line
-        module class sclass def defs undef alias args
-        cbase arg optarg restarg blockarg block_pass args def kwarg kwoptarg
-        kwrestarg send super zsuper yield block send
-        and not or if when case while until while_post
-        until_post for break next redo return resbody
-        kwbegin begin retry preexe postexe iflipflop eflipflop
-        shadowarg
-      ).map(&:to_sym).to_set.freeze
-  end # Meta
-end # Parser
-
 # Library namespace
 module Mutant
   # The empty string used within this namespace
diff --git a/lib/parser-node-list.rb b/lib/parser-node-list.rb
new file mode 100644
index 00000000..c69df653
--- /dev/null
+++ b/lib/parser-node-list.rb
@@ -0,0 +1,25 @@
+# Monkeypatch on parser with a list of allowed nodes.
+# Will be pushed upstream once turning out to be correct.
+module Parser
+  module Meta
+    NODE_TYPES =
+      %w(
+        true false nil int float str dstr str
+        sym dsym xstr regopt regexp array splat
+        array pair kwsplat hash irange erange self
+        lvar ivar cvar gvar const defined? lvasgn
+        ivasgn cvasgn gvasgn casgn mlhs masgn op_asgn
+        op_asgn and_asgn ensure rescue arg_expr
+        or_asgn and_asgn or_asgn back_ref nth_ref
+        match_with_lvasgn match_current_line
+        module class sclass def defs undef alias args
+        cbase arg optarg restarg blockarg block_pass args def kwarg kwoptarg
+        kwrestarg send super zsuper yield block send
+        and not or if when case while until while_post
+        until_post for break next redo return resbody
+        kwbegin begin retry preexe postexe iflipflop eflipflop
+        shadowarg
+      ).map(&:to_sym).to_set.freeze
+  end # Meta
+end # Parser
+