diff --git a/lib/request.js b/lib/request.js
index 34ec754..7c27901 100644
--- a/lib/request.js
+++ b/lib/request.js
@@ -259,8 +259,8 @@ module.exports = {
    */
 
   get idempotent() {
-    return 'GET' == this.method
-      || 'HEAD' == this.method;
+    var idempotents = ['GET','HEAD','PUT','DELETE','OPTIONS','TRACE'];
+    return idempotents.indexOf(this.method) !== -1;
   },
 
   /**