diff --git a/examples/openstack.rb b/examples/openstack.rb
index 3a775b3..f2abf16 100644
--- a/examples/openstack.rb
+++ b/examples/openstack.rb
@@ -8,16 +8,16 @@
   :sudo      => false,
   :logfile   => true,
   :passthrough => {
-    :type                => :openstack,
-    :openstack_auth_url  => 'http://hostname.acme.com:5000/v2.0/tokens',
-    :openstack_username  => 'some_user',
-    :openstack_tenant    => 'tenant_id',
-    :user                => 'ssh_user_id',
-    :keypair             => 'openstack_key_name',
-    :image_ref           => 'c0340afb-577d-1234-87b2-aebdd6d1838f',
-    :flavor_ref          => '547d9af5-096c-1234-98df-7d23162556b8',
-    :openstack_api_key   => 'secret_openstack_key',
-    :key                 => '/path/to/ssh_keys.pem',
+    :type                => :openstack,                                   # Indicate OpenStack provider
+    :openstack_auth_url  => 'http://hostname.acme.com:5000/v2.0/tokens',  # OpenStack API endpoint
+    :openstack_username  => 'some_user',                                  # OpenStack console username
+    :openstack_tenant    => 'tenant_id',                                  # Tenant ID
+    :user                => 'ssh_user_id',                                # SSH login ID
+    :keypair             => 'openstack_key_name',                         # Name of ssh keypair in OpenStack
+    :image_ref           => 'c0340afb-577d-1234-87b2-aebdd6d1838f',       # Image ID in OpenStack
+    :flavor_ref          => '547d9af5-096c-1234-98df-7d23162556b8',       # Flavor ID in OpenStack
+    :openstack_api_key   => 'secret_openstack_key',                       # OpenStack console password
+    :key                 => '/path/to/ssh_keys.pem',                      # SSH key filename
   },
   :sshtunnel => false,
   :verbosity => 1,
@@ -31,14 +31,14 @@
   :sudo      => false,
   :logfile   => true,
   :passthrough => {
-    :type                => :openstack,
-    :openstack_auth_url  => 'http://hostname.acme.com:5000/v2.0/tokens',
-    :openstack_username  => 'some_user',
-    :openstack_tenant    => 'tenant_id',
-    :user                => 'ssh_user_id',
-    :keypair             => 'openstack_key_name',
-    :openstack_api_key   => 'secret_openstack_key',
-    :instance            => ostack.ostack_get_instance_id,
+    :type                => :openstack,                                   # Indicate OpenStack provider
+    :openstack_auth_url  => 'http://hostname.acme.com:5000/v2.0/tokens',  # OpenStack API endpoint
+    :openstack_username  => 'some_user',                                  # OpenStack console username
+    :openstack_tenant    => 'tenant_id',                                  # Tenant ID
+    :user                => 'ssh_user_id',                                # SSH login ID
+    :keypair             => 'openstack_key_name',                         # Name of ssh keypair in OpenStack
+    :openstack_api_key   => 'secret_openstack_key',                       # OpenStack console password
+    :instance            => ostack.ostack_get_instance_id,                # ID of a running OpenStack instance.
   },
   :sshtunnel => false,
   :verbosity => 1,
diff --git a/lib/rouster.rb b/lib/rouster.rb
index e78e070..bb2ef35 100644
--- a/lib/rouster.rb
+++ b/lib/rouster.rb
@@ -199,7 +199,7 @@ def initialize(opts = nil)
 
 	[:openstack_auth_url, :openstack_username, :openstack_tenant, :openstack_api_key,
 	   :key ].each do |r|
-	    raise ArgumentError.new(sprintf('Openstack passthrough requires %s specification', r)) if @passthrough[r].nil?
+	    raise ArgumentError.new(sprintf('OpenStack passthrough requires %s specification', r)) if @passthrough[r].nil?
 	end
 
         if @passthrough.has_key?(:image_ref)