Firefox 5.0.1 is "coming soon," Mozilla announced in a blog post, but did not set a release date. Users running Microsoft Windows or Linux will not see the update.

According to Mozilla, Mac OS X 10.7, aka Lion, contains a bug that causes Firefox 5 to crash when displaying websites that use downloadable fonts.

"We alerted Apple to the problem before the release of 10.7 but they did not fix the problem before 10.7 went to final release," Christopher Blizzard, Mozilla's Web platform director, said on the . "We've changed the font APIs that we're using to newer versions which appear to fix the problem."

The bug in Lion will cause "severe crash problems" for Firefox 5 users if it's not fixed, added Blizzard.

Apple has slated Lion for release this month, and released a "gold master," the final that Blizzard referred to, on July 1. Apple has not announced the ship date for Lion, however.