F-Secure's security software has mistakenly trashed clean files on users' Macs.
The security firm admitted the beta of its Mac OS X software had a "serious false alarm", accidentally detecting safe files as malware.
"The problematic update was removed after two hours," the company said in a blog post. "Beta users who received the update have seen some of their clean files moved to Trash."
The company has released a tool to restore the files. "If you were affected by this issue, please do not empty your Trash in the meantime," it warned.
The fault didn't affect Windows or Linux users, F-Secure said.
Last April, anti-virus vendor McAfee (now part of Intel) was forced into an embarrassing round of compensation to victims of its botched Windows XP signature update that resulted from a false-positive detection.