diff --git a/manifests/init.pp b/manifests/init.pp
index 4faa7ab..ac8fb54 100644
--- a/manifests/init.pp
+++ b/manifests/init.pp
@@ -14,7 +14,7 @@ class mqtt_statsd(
 ){
   include ::pip
 
-  vcsrepo { "$source_dir" :
+  vcsrepo { $source_dir :
     ensure   => latest,
     provider => git,
     revision => $git_revision,
@@ -22,10 +22,10 @@ class mqtt_statsd(
   }
 
   exec { 'install_mqtt_statsd' :
-    command     => "pip install -U $source_dir",
+    command     => "pip install -U ${source_dir}",
     path        => '/usr/local/bin:/usr/bin:/bin/',
     refreshonly => true,
-    subscribe   => Vcsrepo["$source_dir"],
+    subscribe   => Vcsrepo[$source_dir],
     require     => Class['pip'],
   }