added missing namespace
diff --git a/doap.rdf b/doap.rdf
index 7eea685..dac7570 100644
--- a/doap.rdf
+++ b/doap.rdf
@@ -19,6 +19,7 @@
 <rdf:RDF xml:lang="en"
          xmlns="http://usefulinc.com/ns/doap#"
          xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+         xmlns:owl="http://www.w3.org/2002/07/owl#"
          xmlns:asfext="http://projects.apache.org/ns/asfext#"
          xmlns:foaf="http://xmlns.com/foaf/0.1/">