diff --git a/src/networkaccessmanager.cpp b/src/networkaccessmanager.cpp
index 68558714..3397ef7a 100644
--- a/src/networkaccessmanager.cpp
+++ b/src/networkaccessmanager.cpp
@@ -99,12 +99,22 @@ void NetworkAccessManager::setPassword(const QString &password)
 }
 
 // protected:
-QNetworkReply *NetworkAccessManager::createRequest(Operation op, const QNetworkRequest & req, QIODevice * outgoingData)
+QNetworkReply *NetworkAccessManager::createRequest(Operation op, const QNetworkRequest & request, QIODevice * outgoingData)
 {
+    QNetworkRequest req(request);
+
     // Get the URL string before calling the superclass. Seems to work around
     // segfaults in Qt 4.8: https://gist.github.com/1430393
     QByteArray url = req.url().toEncoded();
 
+    // http://code.google.com/p/phantomjs/issues/detail?id=337
+    if (op == QNetworkAccessManager::PostOperation) {
+        QString contentType = req.header(QNetworkRequest::ContentTypeHeader).toString();
+        if (contentType.isEmpty()) {
+            req.setHeader(QNetworkRequest::ContentTypeHeader, "application/x-www-form-urlencoded");
+        }
+    }
+
     // Pass duty to the superclass - Nothing special to do here (yet?)
     QNetworkReply *reply = QNetworkAccessManager::createRequest(op, req, outgoingData);
     if(m_ignoreSslErrors) {