set module version to 1
diff --git a/src/ddoc_cache_opener.erl b/src/ddoc_cache_opener.erl
index 2563cc2..168b455 100644
--- a/src/ddoc_cache_opener.erl
+++ b/src/ddoc_cache_opener.erl
@@ -12,6 +12,7 @@
 
 -module(ddoc_cache_opener).
 -behaviour(gen_server).
+-vsn(1).
 
 -include_lib("couch/include/couch_db.hrl").
 -include_lib("mem3/include/mem3.hrl").