Inform-mode silliness with Emacs 24.4.1 (solved)

Trying to insert curly and square brackets in inform-mode makes Emacs say “Symbol’s value as variable is void: Last command char”
I tried some googling, and it seems this is related to a feature (last-command-char) that has been replaced in recent versions of Emacs.
Elscreen semmes to have had the same problem here: … bug=705436
I wonder what might be the solution with inform-mode?

It looks like this version of inform-mode has been updated to handle the last-command-char -> last-command-event change.

Around four months ago I updated to include this new version of inform-mode.

Thanks for the responses! As Vince suggested, upgrading to inform-mode version 1.6.2 solved it.