How do I create a primary key using two foreign keys in Entity Framework 5 code?

I have an object where the primary key consists of two foreign keys for two other tables. I have a config working with the following, but the table is created with two FK links.

Table:

domain.Entity1
    MorePK (PK, FK, int, not null)
    Entity2_Id (PK, FK, int, not null)
    Entity3_Id (PK, FK, int, not null)
    OtherData (varchar, null)
    Entity2_Id1 (FK, int, null)
    Entity3_Id1 (FK, int, null)

      

        
        
        
      

    

is created from:

public Entity1
{
    public int MorePK { get; set; }
    public int Entity2_Id { get; set; }
    public int Entity3_Id { get; set; }

    public string OtherData { get; set; }

    public virtual Entity2 Entity2 { get; set; }
    public virtual Entity3 Entity3 { get; set; }
}

public Entity2
{
    public int Id { get; set; }
    public virtual List<Entity1> Entity1s { get; set; }
}

public Entity3
{
    public int Id { get; set; }
    public virtual List<Entity1> Entity1s { get; set; }
}

public class Entity1Config : EntityTypeConfiguration<Entity1>
{
    HasKey(k => new { k.MorePK, k.Entity2_Id, k.Entity3_Id });

    HasRequired(p => p.Entity2)
        .WithMany()
        .HasForeignKey(p => p.Entity2_Id);

    HasRequired(p => p.Entity3)
        .WithMany()
        .HasForeignKey(p => p.Entity3_Id);

    Property(x => x.Entity2_Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
    Property(x => x.Entity3_Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
}

      

        
        
        
      

    

If I comment out the line

public virtual List<Entity1> Entity1s { get; set; }

      

        
        
        
      

    

on Entity2 and Entity3, then it generates DB correctly, but I think EF requires correct navigation properties? What's the correct way to get the correct database schema?