A few subtle tweaks will make this exercise much more effective at targeting the lats. But first...

What NOT To Do:

Here the elbows are tracking back, putting an anterior shearing force on the shoulder. This also works more biceps, upper back, and posterior shoulders instead of the lats.

What To Do:

You want your elbows tracking down and back – similar to a row – alleviating shearing force on the front of the shoulder while maximizing lat engagement. If you compare the two, it's obvious that this second movement bypasses the upper back and places way more tension on the lats.

Bonus: Add some handles for a more natural movement.

Related: 5 Lat Exercises Everyone is Doing Wrong

Related: The Unilateral Pulldown