diff --git a/manifests/server/contrib.pp b/manifests/server/contrib.pp
index a896ffd..1d623ec 100644
--- a/manifests/server/contrib.pp
+++ b/manifests/server/contrib.pp
@@ -1,23 +1,22 @@
 # Install the contrib postgresql packaging. See README.md for more details.
 class postgresql::server::contrib (
-  $package_name   = $postgresql::params::contrib_package_name,
-  $package_ensure = 'present'
+  String $package_name = $postgresql::params::contrib_package_name,
+  $package_ensure      = 'present'
 ) inherits postgresql::params {
-  validate_string($package_name)
 
   if $::osfamily == 'Gentoo' {
     fail('osfamily Gentoo does not have a separate "contrib" package, postgresql::server::contrib is not supported.')
   }
 
   package { 'postgresql-contrib':
     ensure => $package_ensure,
     name   => $package_name,
     tag    => 'postgresql',
   }
 
   anchor { 'postgresql::server::contrib::start': }
   -> Class['postgresql::server::install']
   -> Package['postgresql-contrib']
   -> Class['postgresql::server::service']
   anchor { 'postgresql::server::contrib::end': }
 }