Comment 0 for bug 1026869

I've been searching for the solution to this bug for a long time.

Firefox's spell-check, despite my locale being en-US, sets itself to en-GB, en-ZA or something en_US, which isn't even correct.

The problem, it seems, is that Firefox uses whatever spell-checking backends you have installed - aspell, myspell, and hunspell. The result is that Firefox chooses, en-GB as the default spell checker more-often than not. So I uninstalled myspell, hunspell, and a package called firefox-locale-en and now everything is correct - only one spell checker is installed in Firefox.

The language selector, however, always prompts to reinstall these backends whenever it is loaded.