diff --git a/avahi/manifests/init.pp b/avahi/manifests/init.pp
index ee41e76..88566aa 100644
--- a/avahi/manifests/init.pp
+++ b/avahi/manifests/init.pp
@@ -47,9 +47,14 @@ class avahi::daemon {
 #     type   => "_ssh._tcp",
 # }
 #
-define avahi::service($type, $port, $description = "%h", $ensure = "present", $txt = []) {
+define avahi::service($type, $port = "AUTO", $description = "%h", $ensure = "present", $txt = []) {
 
     $srvtype = $type
+    if $port == "AUTO" {
+        $realport = avahi_service_port($srvtype)
+    } else {
+        $realport = $port
+    }
 
     file { "/etc/avahi/services/${name}.service":
         ensure  => $ensure,
diff --git a/avahi/plugins/puppet/parser/functions/avahi_service_port.rb b/avahi/plugins/puppet/parser/functions/avahi_service_port.rb
new file mode 100644
index 0000000..8ad3bbc
--- /dev/null
+++ b/avahi/plugins/puppet/parser/functions/avahi_service_port.rb
@@ -0,0 +1,26 @@
+
+module Puppet::Parser::Functions
+    newfunction(:avahi_service_port, :type => :rvalue) do |args|
+
+	type, name, proto =  /^_([^\.]*)\._([^\.]*)$/.match(args[0]).to_a
+
+	port = nil
+
+	File.open('/etc/services', 'r') do |fd|
+	    while (line = fd.gets)
+		begin
+		    port = /^#{name}[ \t]+(\d+)\/#{proto}.*/.match(line)[1]
+		    break
+		rescue
+		    nil
+		end
+	    end
+	end
+
+	if not port
+	    raise Puppet::ParseError, 'Failed to get port for service %s' % type
+	end
+	port
+
+    end
+end