Bib entry with urldate but no year uses the year of urldate as year

Bib entry with urldate but no year uses the year of urldate as year

Hi i have the following bibliographic entry:
@misc{Wikipedia,
author = {Wikipedia},
title = {{Software performance testing}},
url =
{http://en.wikipedia.org/wiki/Software\_performance\_testing\#Load\_testing},
urldate = {2013-07-10}
}
This entry gets rendered like the following in the bibliography:
if i add a year tag of 2012 to the entry, it becomes:
I think this is wrong, shouldn't i say something like (o.D. is a german
abbreviation for no date, "Besucht am" is "visited at")
Wikipedia o.D. Software Performance testing. Besucht am 10.Juli 2013
? How can i achieve this?