Filtering in EF Generic Repository but still returning ObjectSet<T>

Question

I have a generic Repository that returns an ObjectSet from the objectContext.CreateObjectSet method.

Depending on T, I'd like to use something like :

var objectSet = objectContext.CreateObjectSet<T>();
if (typeof(IAbc).IsAssignableFrom(typeof(T))
{
         return objectSet.Where(x => ((IAbc)x).Abc == "hey");
}

While still being able to return ObjectSet instead of IQueryable.

Does anyone know of a way of accomplishing this or something similar?