diff --git a/src/couch_event_os_sup.erl b/src/couch_event_os_sup.erl
index 6c2b787..ba38f87 100644
--- a/src/couch_event_os_sup.erl
+++ b/src/couch_event_os_sup.erl
@@ -22,6 +22,7 @@
 -behaviour(supervisor).
 -behaviour(config_listener).
 
+-vsn(1).
 
 -export([
     start_link/0,