diff --git a/ptap/ptap.ttl b/ptap/ptap.ttl
index e171faa..eeb1c88 100644
--- a/ptap/ptap.ttl
+++ b/ptap/ptap.ttl
@@ -12,6 +12,7 @@
   ];
   doap:name "PTap";
   doap:license <http://usefulinc.com/doap/licenses/gpl>;
+  lv2:optionalFeature lv2:hardRTCapable ;
 
   ui:ui <urn:fuzzle:ptap#X11UI>;