"The campaign will upgrade software that governs side curtain and seat-mounted side airbags following a small number of inadvertent deployments, most of which occurred in harsh, off-road environments," Fiat-Chrysler said in a statement.
The company said it is unaware of any related accidents or injuries.
The expansion follows a "routine review" by company engineers.
The number of recalled Cherokees in the U.S. for this problem now is estimated at 230,240.
No information about the expanded recall has been posted on the Web site of the National Highway Traffic Safety Administration, which oversees vehicle safety in the U.S.
NHTSA told consumers in the initial recall "if the airbags deploy unexpectedly during vehicle operation, it can increase the risk of personal injury and increase the risk of a crash."
Edmunds says: Fiat-Chrysler said owners will be notified once software becomes available. If you have a concern in the meantime, it's best to contact your dealer.