diff --git a/data/lv2-bundles/files/midifile.ttl b/data/lv2-bundles/files/midifile.ttl
index 7cbb61ec8..8e7fa1bc6 100644
--- a/data/lv2-bundles/files/midifile.ttl
+++ b/data/lv2-bundles/files/midifile.ttl
@@ -4,6 +4,7 @@
 @prefix lv2:   <http://lv2plug.in/ns/lv2core#> .
 @prefix opts:  <http://lv2plug.in/ns/ext/options#> .
 @prefix patch: <http://lv2plug.in/ns/ext/patch#> .
+@prefix unit:  <http://lv2plug.in/ns/extensions/units#> .
 
 <http://kxstudio.sf.net/carla/plugins/midifile>
     a lv2:UtilityPlugin, lv2:Plugin ;