diff --git a/src/comm/MAVLinkProtocol.cc b/src/comm/MAVLinkProtocol.cc
index cee05d9acb3f0446049ffae02d20d8dd0b8414d5..e14d6bdd60cf55e23d28e8527f2c701ec1830256 100644
--- a/src/comm/MAVLinkProtocol.cc
+++ b/src/comm/MAVLinkProtocol.cc
@@ -291,11 +291,14 @@ void MAVLinkProtocol::receiveBytes(LinkInterface* link, QByteArray b)
             // Log data
             if (m_loggingEnabled && m_logfile)
             {
-                uint8_t buf[MAVLINK_MAX_PACKET_LEN+sizeof(quint64)];
+                uint8_t buf[MAVLINK_MAX_PACKET_LEN+sizeof(quint64)] = {0};
                 quint64 time = QGC::groundTimeUsecs();
                 memcpy(buf, (void*)&time, sizeof(quint64));
                 // Write message to buffer
-                int len = mavlink_msg_to_send_buffer(buf+sizeof(quint64), &message);
+                mavlink_msg_to_send_buffer(buf+sizeof(quint64), &message);
+                //we need to write the maximum package length for having a
+                //consistent file structure and beeing able to parse it again
+                int len = MAVLINK_MAX_PACKET_LEN + sizeof(quint64);
                 QByteArray b((const char*)buf, len);
                 if(m_logfile->write(b) != len)
                 {