Raytheon Co. and its San Diego workforce received a four-year U.S. Navy electronics contract worth $41.6 million.

Under the deal, Raytheon’s Integrated Defense Systems unit will make improvements to a defense system for aircraft carriers and amphibious ships. Work on the Ship Self Defense System MK2 will last through September 2017, according to a Defense Department announcement.

The Naval Sea Systems Command of Washington, D.C. awarded the work, technically a contract modification.

Ninety-nine percent of the contract will be completed in San Diego. Remaining work will go to staff in Middletown, R.I.

Raytheon is a $24 billion company based in Massachusetts.