Default Scope - Disambiguate Problem

Having trouble with a default scope find() method in yii2.

When the default scope is used to find a single entity instance

$c = Customer::findOne(1);

I am receiving a

SQLSTATE[23000]: Integrity constraint violation: 1052 Column ‘id’ in where clause is ambiguous

The default scope is defined as follows (basically trying to restrict ability to view customers unless logged in user is listed in customer_user table).

public static function find()


      return parent::find()->leftJoin('customer_user', ' = customer_user.customer_id')



How do I disambiguate the default model (Customer) id column?