Check Point is offering its ForceField browser virtualisation security software for free.
But the deal is only available to people who download it between 2pm UK time today (12 August) and 2pm tomorrow (13 August).
The offer is valid for a full year's license for one PC (normally $30).
The software developer explains: "A number of recent studies show that over half of all Web sites, including many of the leading search, social networking and shopping sites are infested with some form of malware, which work by taking advantage of browser or operating system vulnerabilities.
"Once new browser vulnerabilities have been discovered, they can be exploited almost immediately. Unfortunately, there is a time lapse before a patch can be deployed.
"ForceField protects against the latest threats and closes an attacker’s window of opportunity by providing immediate protection. This demonstrates that patching alone is not enough and that layered protection is the best defence."