The Nuvi user whom I have mentioned before reported that the routing between Tapiola, Espoo and Töölö, Helsinki was broken for some weeks until it started working again with yesterday's map. The only explanation that I can think of is that I shrunk the map tile to get rid of the TRE header corruption that prevented the gmapsupp.img from being generated. I suspect that there has been some overflow in the map tile before, but I just haven't noticed it myself. Would it be possible to add some more consistency checks, such as assertions, exceptions or error logging, to the mkgmap backend? Silent data corruption is not nice. Marko