Laravel 4: Adding where clause to a join condition

It says in the laravel docs that it is possible to add where clause on a join, but whenever I try in my code using the where clause, I get the error: Call to undefined method Illuminate\Database\Query\JoinClause::where(). Anyone knows how to add where clause in a join clause?

Laravel Website Example:

DB::table('users')
->join('contacts', function($join)
{
  $join->on('users.id', '=', 'contacts.user_id')
  ->where('contacts.user_id', '>', 5);
})
->get();

Code I'm trying to implement:

DB::table('users')
->join('contacts', function($join)
{
  $current_date = date('Y-m-d');
  $join->on('users.id', '=', 'contacts.user_id')
  ->where('contacts.effective_date', '>=', $current_date);
})
->get();