Requesting a rout via QGeoRoutingManager fails with language set to QLocale::C

Requesting a rout via QGeoRoutingManager fails with language set to QLocale::C.
This might no be a Qt specific bug but a bug I the navteq service used by the routing plugin.

Resulting example request url:
http://prd.lbsp.navteq.com/routing/6.2/calculateroute.xml?referer=qtlocationapi&token=152022572f0e44e07489c35cd46fa246&waypoint0=50.8211708069,19.0568447113&waypoint1=50.7222747803,19.0116100311&mode0=fastestNow;car&alternatives=0&linkattributes=sh,le&maneuverattributes=po,tt,le,di,li&routeattributes=sm,sh,bb,lg&legattributes=links,maneuvers&departure=2011-08-11T13:15:35Z&instructionformat=text&language=C

Resulting error:
<e:Error xmlns:e="http://www.navteq.com/lbsp/Errors/1" type="ApplicationError" subtype="InvalidInputData">
<Details>
Expected format: a single language subtag composed of 2 or 3 letters potentially followed by extended language subtag separated by hyphen and composed of 2 or 3 letters
</Details>
<AdditionalData key="language">C</AdditionalData>
</e:Error>

A simple workaround:
if(m_routingManager->locale().language() == QLocale::C)
m_routingManager->setLocale(QLocale(QLocale::English));