diff --git a/puppet/manifests/init.pp b/puppet/manifests/init.pp
index 5849d70..34182f8 100644
--- a/puppet/manifests/init.pp
+++ b/puppet/manifests/init.pp
@@ -1,6 +1,17 @@
 
 # Install and configure Puppet client.
 #
+# === Global variables
+#
+#   $puppet_server:
+#       Hostname of puppet server. Defaults to 'puppet'.
+#
+#   $puppet_keylength:
+#       Length of client keys. Defaults to 2048.
+#
+#   $puppet_diffargs:
+#       Arguments for puppet's use of diff. Unset by default.
+#
 class puppet::client {
 
     tag("bootstrap")
@@ -13,10 +24,6 @@ class puppet::client {
         $puppet_keylength = "2048"
     }
 
-    if ! $puppet_diffargs {
-        $puppet_diffargs = "-u"
-    }
-
     case $operatingsystem {
         openbsd: { $vardir = "/var/puppet" }
         default: { $vardir = "/var/lib/puppet" }
diff --git a/puppet/templates/puppet.conf.erb b/puppet/templates/puppet.conf.erb
index 8670b0b..1e5a08c 100644
--- a/puppet/templates/puppet.conf.erb
+++ b/puppet/templates/puppet.conf.erb
@@ -39,9 +39,11 @@
     # The bit length of keys.
     keylength = <%= puppet_keylength %>
 
+<% if has_variable?("puppet_diffargs") -%>
     # Arguments for puppet's use of diff
     diff_args = <%= puppet_diffargs %>
 
+<% end -%>
 <% if puppetversion[/\d+/].to_i >= 2 -%>
 [agent]
     # Ignore site manifest when run as agent. Fixes warnings about