diff --git a/lib/multi_xml/parsers/libxml.rb b/lib/multi_xml/parsers/libxml.rb
index 308ed8e..406c0b8 100644
--- a/lib/multi_xml/parsers/libxml.rb
+++ b/lib/multi_xml/parsers/libxml.rb
@@ -35,14 +35,12 @@ def to_hash
     end
 
     module Node #:nodoc:
-      CONTENT_ROOT = '__content__'.freeze unless defined?(CONTENT_ROOT)
-
       # Convert XML document to hash
       #
       # hash::
       #   Hash to merge the converted element into.
       def to_hash(hash={})
-        node_hash = {CONTENT_ROOT => ''}
+        node_hash = {MultiXml::CONTENT_ROOT => ''}
 
         # Insert node hash into parent hash correctly.
         case hash[name]
@@ -56,13 +54,13 @@ def to_hash(hash={})
           if c.element?
             c.to_hash(node_hash)
           elsif c.text? || c.cdata?
-            node_hash[CONTENT_ROOT] << c.content
+            node_hash[MultiXml::CONTENT_ROOT] << c.content
           end
         end
 
         # Remove content node if it is empty
-        if node_hash[CONTENT_ROOT].strip.empty?
-          node_hash.delete(CONTENT_ROOT)
+        if node_hash[MultiXml::CONTENT_ROOT].strip.empty?
+          node_hash.delete(MultiXml::CONTENT_ROOT)
         end
 
         # Handle attributes
diff --git a/lib/multi_xml/parsers/nokogiri.rb b/lib/multi_xml/parsers/nokogiri.rb
index 295ec51..661fedb 100644
--- a/lib/multi_xml/parsers/nokogiri.rb
+++ b/lib/multi_xml/parsers/nokogiri.rb
@@ -33,14 +33,12 @@ def to_hash
         end
 
         module Node #:nodoc:
-          CONTENT_ROOT = '__content__'.freeze unless defined?(CONTENT_ROOT)
-
           # Convert XML document to hash
           #
           # hash::
           #   Hash to merge the converted element into.
           def to_hash(hash={})
-            node_hash = {CONTENT_ROOT => ''}
+            node_hash = {MultiXml::CONTENT_ROOT => ''}
 
             # Insert node hash into parent hash correctly.
             case hash[name]
@@ -54,13 +52,13 @@ def to_hash(hash={})
               if c.element?
                 c.to_hash(node_hash)
               elsif c.text? || c.cdata?
-                node_hash[CONTENT_ROOT] << c.content
+                node_hash[MultiXml::CONTENT_ROOT] << c.content
               end
             end
 
             # Remove content node if it is empty
-            if node_hash[CONTENT_ROOT].strip.empty?
-              node_hash.delete(CONTENT_ROOT)
+            if node_hash[MultiXml::CONTENT_ROOT].strip.empty?
+              node_hash.delete(MultiXml::CONTENT_ROOT)
             end
 
             # Handle attributes
diff --git a/lib/multi_xml/parsers/rexml.rb b/lib/multi_xml/parsers/rexml.rb
index dc85b16..d55f7fe 100644
--- a/lib/multi_xml/parsers/rexml.rb
+++ b/lib/multi_xml/parsers/rexml.rb
@@ -6,8 +6,6 @@ module Rexml #:nodoc:
       extend self
       def parse_error; ::REXML::ParseException; end
 
-      CONTENT_ROOT = '__content__'.freeze unless defined?(CONTENT_ROOT)
-
       # Parse an XML Document string or IO into a simple hash using REXML
       #
       # xml::
@@ -72,7 +70,7 @@ def merge_texts!(hash, element)
           # must use value to prevent double-escaping
           texts = ''
           element.texts.each { |t| texts << t.value }
-          merge!(hash, CONTENT_ROOT, texts)
+          merge!(hash, MultiXml::CONTENT_ROOT, texts)
         end
       end