How do I lock my nexus 4's files from pc connections?

[smilodon142]

When I plug my nexus 4 into my computer I can open the phone and get to all the files without putting in my pass code to unlock my phone. My old S3 and my nexus 7 both require me to unlock the device to access the files. The nexus 4 and nexus 7 both run kitkat. I want to make it so my nexus 4 dose the same, is their a setting that I cant find or somthing?