diff --git a/lib/twitter.js b/lib/twitter.js
index 1dbf3e27..e663dfc0 100644
--- a/lib/twitter.js
+++ b/lib/twitter.js
@@ -134,12 +134,17 @@ Twitter.prototype.__request = function(method, path, params, callback) {
 
   // Pass form data if post
   if (method === 'post') {
-    var formKey = 'form';
+    if (this.options.request_options.json) {
+      options.body = params;
+    }
+    else {
+      var formKey = 'form';
 
-    if (typeof params.media !== 'undefined') {
-      formKey = 'formData';
+      if (typeof params.media !== 'undefined') {
+        formKey = 'formData';
+      }
+      options[formKey] = params;
     }
-    options[formKey] = params;
   }
 
   // Promisified version
@@ -158,7 +163,7 @@ Twitter.prototype.__request = function(method, path, params, callback) {
           if (data === '') {
             data = {};
           }
-          else {
+          else if (typeof data === 'string') {
             data = JSON.parse(data);
           }
         }