Fix changes introduced in https://github.com/request/request/pull/1282

request.js

@@ -1482,7 +1482,7 @@ Request.prototype.json = function (val) {
 
   self._json = true
   if (typeof val === 'boolean') {
-    if (self.body !== undefined) {
+    if (self.body !== undefined && self.getHeader('content-type') !== 'application/x-www-form-urlencoded') {
       self.body = safeStringify(self.body)
       if (!self.hasHeader('content-type')) {
         self.setHeader('content-type', 'application/json')

tests/test-form-urlencoded.js

@@ -0,0 +1,44 @@
+'use strict'
+
+var http = require('http')
+  , request = require('../index')
+  , tape = require('tape')
+
+
+tape('application/x-www-form-urlencoded', function(t) {
+
+  var server = http.createServer(function(req, res) {
+
+    t.equal(req.headers['content-type'], 'application/x-www-form-urlencoded')
+    t.equal(req.headers.accept, 'application/json')
+
+    var data = ''
+    req.setEncoding('utf8')
+
+    req.on('data', function(d) {
+      data += d
+    })
+
+    req.on('end', function() {
+      t.equal(data, 'some=url&encoded=data')
+
+      res.writeHead(200)
+      res.end('done')
+
+      t.end()
+    })
+  })
+
+  server.listen(8080, function() {
+
+    request.post('http://localhost:8080', {
+      form: {some: 'url', encoded: 'data'},
+      json: true
+    }, function(err, res, body) {
+      t.equal(err, null)
+      t.equal(res.statusCode, 200)
+      t.equal(body, 'done')
+      server.close()
+    })
+  })
+})