Is there a way to create a segmentation list to pull in Salesforce Leads?

I'm trying to create a Pardot segmentation list that pulls in Salesforce Leads only (so contacts who have not yet been converted into an account/contact). I know they are all Prospects in Pardot, but I'm wondering if there is a way to do this. So far I have tried using Account Name is Empty, Lead Status is not Empty, Company is Unassigned. None of those worked for me. 

Any help would be appreciated!

Thanks!