Passing explicit database port causes type error

Sylius Installer fail

Creating the "app/config/parameters.yml" file
Some parameters are missing. Please provide them.
database_driver ('%env(SYLIUS_DATABASE_DRIVER)%'):
database_host ('%env(SYLIUS_DATABASE_HOST)%'):
database_port ('%env(SYLIUS_DATABASE_PORT)%'):
database_name ('%env(SYLIUS_DATABASE_NAME)%'):
database_user ('%env(SYLIUS_DATABASE_USER)%'):
database_password ('%env(SYLIUS_DATABASE_PASSWORD)%'):
mailer_transport ('%env(SYLIUS_MAILER_TRANSPORT)%'):
mailer_host ('%env(SYLIUS_MAILER_HOST)%'):
mailer_user ('%env(SYLIUS_MAILER_USER)%'):
mailer_password ('%env(SYLIUS_MAILER_PASSWORD)%'):
secret ('%env(SYLIUS_SECRET)%'):
env(SYLIUS_DATABASE_DRIVER) (pdo_mysql): pdo_pgsql
env(SYLIUS_DATABASE_HOST) (127.0.0.1):
env(SYLIUS_DATABASE_PORT) (null): 5432
env(SYLIUS_DATABASE_NAME) (sylius):
env(SYLIUS_DATABASE_USER) (root): sylius
env(SYLIUS_DATABASE_PASSWORD) (null): sylius
env(SYLIUS_MAILER_TRANSPORT) (smtp):
env(SYLIUS_MAILER_HOST) (127.0.0.1):
env(SYLIUS_MAILER_USER) (null):
env(SYLIUS_MAILER_PASSWORD) (null):
env(SYLIUS_SECRET) (EDITME): EDITME
> Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache

In ValidateEnvPlaceholdersPass.php line 54:

  Invalid type for env parameter "env(SYLIUS_DATABASE_PORT)". Expected "string", but got "int".