The statement "The spelling with d was a mistake" does not seem to be correct. The letter 'd' was added in the English texts only, which reflects the true English pronunciation of the word. The inclusion of the 'd' sound is a phonological phenonmenon (associated with English phonology) that appears in many other English and loan words. For example, thunner became thunder, Amiral became Admiral and so on.
Aursani 19:20, 23 March 2010 (UTC)