Firstable

In Great English Mistakes, published in 2008, I write:

Firstable
A classic mistake is to write this because you have heard a speaker say it at a meeting. But you haven’t. What he actually said was, First of all, I would like to thank …

I can’t remember when I first saw it in written work from a student – and I remember being astonished when I did – but it wasn’t by any means new to me when I wrote that.

Now the Language Log reports that it is appearing on the internet from native speakers with quotations going back to 1996. It is perfectly understandable from a non-native but surely there is something wrong when native speakers use it.