diff --git a/python/manifests/init.pp b/python/manifests/init.pp
index f572bb5..4287ef6 100644
--- a/python/manifests/init.pp
+++ b/python/manifests/init.pp
@@ -179,6 +179,9 @@ define python::pip::install($source=undef) {
       source => $source,
     }
 
+    # Use exec to install from local files, pip package provider does not
+    # support extra arguments. --no-deps --no-index stops pip from accessing
+    # pypi.
     exec { "pip-install-${filename}":
       refreshonly => true,
       path        => '/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin',