diff --git a/apt/manifests/init.pp b/apt/manifests/init.pp
index 65f56f8..1b7b218 100644
--- a/apt/manifests/init.pp
+++ b/apt/manifests/init.pp
@@ -3,8 +3,8 @@ class apt {
     file { "/var/cache/apt/local-archives":
         ensure => directory,
         mode   => "0755",
-        owner  => root,
-        group  => root,
+        owner  => "root",
+        group  => "root",
     }
 
     exec { "apt-get-update":
@@ -16,7 +16,7 @@ class apt {
 }
 
 
-# Install common packages for using PPA's.
+# Install common packages for using PPAs.
 #
 class apt::ppa::helper {
 
@@ -66,7 +66,7 @@ define apt::ppa($ensure = "present") {
             }
         }
         default: {
-            fail("test")
+            fail("apt::ppa: Invalid value ${ensure} for ensure.")
         }
     }
 
@@ -135,8 +135,8 @@ class apt::cacher {
         source => [ "puppet:///files/apt/apt-cacher.conf",
                     "puppet:///modules/apt/apt-cacher.conf", ],
         mode   => "0644",
-        owner  => root,
-        group  => root,
+        owner  => "root",
+        group  => "root",
         notify => Service["apt-cacher"],
     }
 
@@ -148,6 +148,7 @@ class apt::cacher {
 
 }
 
+
 # Mirroring tool for apt repositories
 #
 # === Global variables
@@ -189,8 +190,8 @@ class apt::mirror {
         },
         content => template("apt/mirror.list.erb"),
         mode    => "0644",
-        owner   => root,
-        group   => root,
+        owner   => "root",
+        group   => "root",
         require => Package["apt-mirror"],
     }
 
@@ -228,8 +229,8 @@ define apt::package($ensure, $source) {
         },
         source  => $source,
         mode    => "0644",
-        owner   => root,
-        group   => root,
+        owner   => "root",
+        group   => "root",
         require => File["/var/cache/apt/local-archives"],
     }
 
@@ -316,8 +317,8 @@ define apt::repo($ensure, $source, $dist="", $components="main",
     file { "/etc/apt/sources.list.d/${name}.list":
         ensure  => $ensure,
         mode    => "0644",
-        owner   => root,
-        group   => root,
+        owner   => "root",
+        group   => "root",
         content => $content,
         notify  => Exec["apt-get-update"],
     }
@@ -349,8 +350,8 @@ define apt::repo($ensure, $source, $dist="", $components="main",
         file { "/etc/apt/preferences.d/${name}.pref":
             ensure  => $ensure,
             mode    => "0644",
-            owner   => root,
-            group   => root,
+            owner   => "root",
+            group   => "root",
             content => $label ? {
                 ""      => "Package: *\nPin: origin ${origin}\nPin-Priority: ${priority}\n",
                 default => "Package: *\nPin: release l=${label}\nPin-Priority: ${priority}\n",