The War Z will now be known as Infestation: Survivor Stories, following a copyright claim.
According to a post on the game's official forums, the change will not affect the game.
"This change has come about primarily as a result of some confusion and trademark issues with a similarly titled property," the post reads.
"While we were reluctant to rename the game so long after launch, especially with nearly 1 million registered players, it was ultimately decided to be in the best interest of our existing community as well as future players in order to eliminate confusion."
It's not the first controversy for the Hammerpoint Interactive developed title: the game has been the victim of security breaches, and was temporarily removed from Steam following concerns the publisher falsely advertised the title.