diff --git a/pisi-spec.rng b/pisi-spec.rng
index 1605c32b..829fdccb 100644
--- a/pisi-spec.rng
+++ b/pisi-spec.rng
@@ -324,6 +324,7 @@
                 <value>Intel-SDP</value>
                 <value>Interbase-1.0</value>
                 <value>Introversion</value>
+                <value>IRDL</value>
                 <value>JDOM</value>
                 <value>JNIC</value>
                 <value>JPython</value>