A free whole-disk encryption tool will no longer be maintained, according to a recent announcement.

On Wednesday, those who visited a project page for the popular open-source software, TrueCrypt, first saw the surprising message warning them to instead migrate to similar software, BitLocker.

“Warning: Using TrueCrypt is not secure as it may contain unfixed security issues,” the message said.

The decision to stop development of the software apparently coincided with the end-of-support of Windows XP, an operating system that supported the encryption software, the message said.

The news comes after iSec Partners concluded its first phase of a security audit of the software in February. According to the audit, there were no backdoors in the software, though some vulnerabilities were detailed in the report.