BlackBerry Ltd. accused Snap Inc. of using its patented messaging technology in the Snapchat app, mirroring a similar complaint the Canadian software developer brought last month against Facebook Inc.

BlackBerry chief executive officer John Chen has been working to find additional sources of revenue as investors express concern over growth rates at the company’s core security-focused software business. That has sent the company hunting through its library of wireless tech and messaging patents to find opportunities for more licensing deals, and lawsuits.

BlackBerry alleged in March that Facebook’s apps copy old methods for displaying messages from the days when BlackBerry’s messaging service was a world leader. The company has also managed to secure settlements from Cisco Systems Inc., phone maker BLU Products and communications tech firm Avaya Holdings Corp.

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The complaint accuses Snap of infringing six patents issued in 2012 and 2014. Two of those are among the seven BlackBerry patents that were in the suit against Facebook filed March 6.

Representatives of Venice, California-based Snap declined to comment.