diff --git a/pisi-spec.rng b/pisi-spec.rng
index 15200613..e9753786 100644
--- a/pisi-spec.rng
+++ b/pisi-spec.rng
@@ -440,6 +440,7 @@
                 <value>Resounding</value>
                 <value>RiceBSD</value>
                 <value>Roadrunner</value>
+                <value>Royalty-Free</value>
                 <value>Ruby</value>
                 <value>SGI-B</value>
                 <value>SGI-B-1.1</value>