Clonezilla restore Ubuntnu 16.04 SecureBoot

I'm attempting to restore a custom Ubuntu 16.04 image to a machine with SecureBoot enabled. It restores fine, but when I reboot, I get a message that the "Operating System Loader signature not found in SecureBoot database ('db')." The image was taken machine with SecureBoot enabled as well. Did I miss a step? I'd like not to have to disable SecureBoot, thanks.