heroku [Symfony\Component\Debug\Exception\FatalThrowableError] Class 'Faker\Factory' not found

I have problems with heroku when I do : "heroku run php artisan db:seed"

 $ heroku run php artisan db:seed
 Running php artisan db:seed on jaquenews... starting, run.7385 (Free)
 Running php artisan db:seed on jaquenews... connecting, run.7385 (Free)
 Running php artisan db:seed on jaquenews... up, run.7385 (Free)
 **************************************
 *     Application In Production!     *
 **************************************

 Do you really wish to run this command? (yes/no) [no]:
 > yes
 yes

 Seeding: UsersTableSeeder

 [Symfony\Component\Debug\Exception\FatalThrowableError]
 Class 'Faker\Factory' not found

via Chebli Mohamed