Revenue from the contract will show up in the Ottawa company's fourth-quarter results.
"We have been providing our products and services to this customer since 2001," stated chief executive Ken Kirkpatrick.
"We value our long-term business relationship with this important customer, and we are confident that our business will continue to expand."
OSI's stock price fell four per cent to 24 cents by mid-morning Monday.
This quarter, OSI signed a contract to supply software to UK Royal Navy submarines for an undisclosed amount. The defence firm also got $2.8 million from the United States Army to develop medical training technology.
The firm reported a $1.3 million net loss in its third quarter last month as revenues halved year-over-year to $3.3 million.