In a letter sent Thursday to Director of National Intelligence Tulsi Gabbard, the lawmakers say that because VPNs obscure a user’s true location, and because intelligence agencies presume that communications of unknown origin are foreign, Americans may be inadvertently waiving the privacy protections they’re entitled to under the law.

Several federal agencies, including the FBI, NSA, and FTC, have recommended that consumers use VPNs to protect their privacy. But following that advice may inadvertently cost Americans the very protections they’re seeking.

The letter was signed by members of the Democratic Party’s progressive flank: Senators Ron Wyden, Elizabeth Warren, Edward Markey, and Alex Padilla, along with Representatives Pramila Jayapal and Sara Jacobs.