diff --git a/bin/builder_web_app.ml b/bin/builder_web_app.ml
index 1433245..6b699c2 100644
--- a/bin/builder_web_app.ml
+++ b/bin/builder_web_app.ml
@@ -26,7 +26,7 @@ open Cmdliner
 
 let datadir =
   let doc = "data directory" in
-  Arg.(value & opt dir "/var/db/builder-web/" & info [ "-d"; "--datadir" ] ~doc)
+  Arg.(value & opt dir "/var/db/builder-web/" & info [ "d"; "datadir" ] ~doc)
 
 let port =
   let doc = "port" in