Your image looks just fine for
Polyxenus lagurus. Jürgen Peters of Insektenfotos.de finds them on the (outdoor) walls of his house all the time, so it's not too surprising you would find one inside incidentally.
If you want many, many images for comparison go to
this search page and enter "Polyxenus" or "Pinselfüßer" ... image galore
Cheers, Arp