Browser developer Mozilla on Tuesday endorsed a federal antitrust bill that would prohibit the largest online tech companies from giving their own products and services preferential treatment.

The American Innovation and Choice Online Act, introduced last year by Senators Amy Klobuchar (D-Minnesota) and Chuck Grassley (R-Iowa), could prevent Google from returning search results that prioritize its own products, and Amazon from using data gleaned from third-party sellers on the platform to compete against them.

Mozilla, which develops the Firefox browser, said Tuesday it “cannot effectively compete without this antitrust law.”

“We are disadvantaged by the fact that current and future Firefox users, many of whom are privacy and security focused, cannot easily install and keep Firefox as their preferred browser because of confusing operating system messages and settings,” Mozilla attorney Urmika Devi Shah wrote in a company blog post.

Shah argues that the proposed law would result in improved privacy protections for consumers.

“Our view is that self-preferencing is preventing internet development from being more private and secure than it is today,” Shah writes.

She adds that even though Mozilla developed technology that aims to combat cross-site tracking, the company “never released this technology to Firefox users on iOS because of App Store rules preferring Apple’s own browser engine over alternatives.”

The Justice Department has gone on record in favor of the bill, while large companies including Apple and Google oppose it.

Google’s chief legal officer Kent Walker warned earlier this year that new restrictions could hinder search users.

“If you search for a place or an address, we may not be able to show you directions from Google Maps in your results,” Kent Walker, the company’s chief legal officer, said in a January blog post.

Apple opposes both the American Innovation and Choice Online Act and a separate antitrust bill, the Open App Markets Act, which would require app stores with more than 50 million U.S. users to enable app downloads from from outside sources.

Google already enables those outside downloads, but Apple does not. Apple CEO Tim Cook argues that allowing iPhone and iPad users to download apps from third party sources poses privacy and security risks.

Earlier this year, the Senate Commerce Committee voted 16-6 to advance the American Innovation and Choice Online Act. It’s not yet clear whether the full Senate will vote on the bill before the summer recess.

Browser developer Mozilla on Tuesday backed a federal antitrust bill that would prohibit the largest online tech companies from giving their own products and services preferential treatment.