Django Circular Model Dependency

I have a circular dependency in my Django models, such that model A has a foreign key reference to B, while B has a many-to-many reference to A. I've consulted other SO posts and have used the string model names instead of the actual classes, but to no avail. Here are abbreviated versions of my two classes: User model ``` import listings.models class User(models.Model): ... favorites = models.ManyToManyField('listings.models.Listing') ``` Listing model ``` import users.models class Listing(models.Model): ... owner = models.ForeignKey('users.models.User') ``` Every time I attempt to run syncdb, it outputs the following error: Error: One or more models did not validate: users.user: 'favorites' has an m2m relation with model listings.models.Listing, which has either not been installed or is abstract. listings.listing: 'owner' has a relation with model users.models.User, which has either not been installed or is abstract. How do I resolve this without sacrificing the established relationship?