diff --git a/manifests/init.pp b/manifests/init.pp
index 33d5b14..72aa908 100644
--- a/manifests/init.pp
+++ b/manifests/init.pp
@@ -1,12 +1,22 @@
 # install everything required to be a git client
 class git (
+  $ensure  = present,
   $sources = "https://git-osx-installer.googlecode.com/files/git-1.8.3.2-intel-universal-snow-leopard.dmg"
 ){
 
   include git::params
 
-  package { $git::params::packages:
-    ensure => present,
-    source => $sources,
+  case $::operatingsystem {
+    'Darwin': {
+      package { $git::params::packages:
+        ensure => $ensure,
+        source => $sources
+      }
+    }
+    default: {
+      package { $git::params::packages:
+        ensure => $ensure
+      }
+    }
   }
 }
diff --git a/manifests/params.pp b/manifests/params.pp
index 7f0018c..d235bb9 100644
--- a/manifests/params.pp
+++ b/manifests/params.pp
@@ -1,11 +1,11 @@
 # = Class: git::params
 #
 class git::params {
-  case $operatingsystem {
+  case $::operatingsystem {
     'Debian': { $packages = 'git' }
     'Ubuntu': { $packages = 'git-core' }
     'Ubuntu': {
-      case $operatingsystemrelease {
+      case $::operatingsystemrelease {
         'Hardy', 'Lucid': { $packages = 'git-core' }
         default: { $packages = 'git' }
       }
@@ -24,6 +24,6 @@
         require => File['/usr/local/bin'],
       }
     }
-    default:   { fail("No git package known for operating system ${operatingsystem}") }
+    default:   { fail("No git package known for operating system ${::operatingsystem}") }
   }
 }