diff --git a/actionpack/lib/action_view/helpers/javascripts/prototype.js b/actionpack/lib/action_view/helpers/javascripts/prototype.js
index a9195b89e6cb2287ce56640c4ef2c53271f6950d..5c939795c817ef3d20cc73a0a9dc30eaa0297d1c 100644
--- a/actionpack/lib/action_view/helpers/javascripts/prototype.js
+++ b/actionpack/lib/action_view/helpers/javascripts/prototype.js
@@ -704,7 +704,7 @@ Ajax.Request.prototype = Object.extend(new Ajax.Base(), {
     var requestHeaders =
       ['X-Requested-With', 'XMLHttpRequest',
        'X-Prototype-Version', Prototype.Version,
-       'Accept', 'text/javascript, text/xml, text/html, */*' ];
+       'Accept', 'text/javascript, text/html, application/xml, text/xml, */*'];
 
     if (this.options.method == 'post') {
       requestHeaders.push('Content-type',
diff --git a/railties/html/javascripts/prototype.js b/railties/html/javascripts/prototype.js
index a9195b89e6cb2287ce56640c4ef2c53271f6950d..5c939795c817ef3d20cc73a0a9dc30eaa0297d1c 100644
--- a/railties/html/javascripts/prototype.js
+++ b/railties/html/javascripts/prototype.js
@@ -704,7 +704,7 @@ Ajax.Request.prototype = Object.extend(new Ajax.Base(), {
     var requestHeaders =
       ['X-Requested-With', 'XMLHttpRequest',
        'X-Prototype-Version', Prototype.Version,
-       'Accept', 'text/javascript, text/xml, text/html, */*' ];
+       'Accept', 'text/javascript, text/html, application/xml, text/xml, */*'];
 
     if (this.options.method == 'post') {
       requestHeaders.push('Content-type',