Firefox is still chipping away at Internet Explorer's market share.

The open-source browser now makes up 8 percent of the marker, up from 7.38 percent in April. Explorer's slice of the pie shrunk by nearly one percent to 87.23 percent, according to NetApplications.com.

Although Explorer remains firmly in control, Firefox is consistently increasing its share by between half and one percent from month to month, suggesting it is extending beyond a core of tech-savvy users, NetApplications claimed.

It compiled the browser data from over 40,000 websites monitored by its HitsLink.com service.

Firefox's steady increase reflects that it has proved itself as a secure and reliable browser, and that it is a viable contender in the market, said Dan Shapero, NetApplications.com's chief operating officer. "The message for webmasters is clear: make sure your website is compatible with Firefox, because more and more of your visitors are using it."

Firefox could add to its momentum if it starts to gain converts among IT departments in large companies, Shapero said. Becoming the standard browser in large companies, a segment where its adoption has been limited so far, will give a rapid boost to its market share.