Storage: Unexpected token when piping from a request

Hi all, what I do is a binary signed POST form the client, passing a Blob into it.

My nodejs server then checks if the POST is valid and tries to pipe the req into a writeStream created form a bucket:

var storage = gcloud.storage({
        keyFilename: config.PATH_TO_GCLOUD_KEY,
        projectId: config.GCLOUD_PROJECT_ID
    });
// Reference an existing bucket.
var resourceBucket = storage.bucket(config.GCLOUD_RESOURCE_BUCKET);
var wrStream =  resourceBucket.file("123").createWriteStream();

/* ... in the POST handler ... */

req.pipe(wrStream);

But the pipe always end with this Object.Parse exception:

undefined:1
���0�0�c0�(��   *�H��
*�H��

 ^
SyntaxError: Unexpected token �
    at Object.parse (native)
    at /Users/myuser/dev-exp/myProject/node_modules/gcloud/lib/common/connection.js:185:31
    at fs.js:271:14
    at Object.oncomplete (fs.js:107:15)

Am I missing something?