How to turn off "Shake to wake camera" on Nexus 5?

Ages ago, while running Lollipop, I found a setting to allow activation of the camera whilst locked. All you have to do is shake the phone. I'll give that a try, I thought. After all, I can always cancel it if I don't like it. However, the thing is way too sensitive and has been driving me mad taking photos of pocket lint and my feet mostly I can't find the setting to turn it off, despite a great deal of menu exploring and even checking the 'similar questions' panel currently to my right as I type. Upgrading to Marshmallow hasn't got rid of it. I've got a sneaky suspicion it's a function of a 3rd-party app since there's nothing obvious in the Android settings screen or in the app settings. Has anyone else come across this or actually figured how to disable it?