--- dune.orig	2019-11-30 19:04:21.781276400 +0100
+++ dune	2019-11-30 19:03:52.531276564 +0100
@@ -1,9 +1,9 @@
 (env
  (dev
-  (flags (:standard -bin-annot -w -22))
+  (flags (:standard -bin-annot -w -22 -warn-error -A))
   (ocamlopt_flags -g -O3 -unbox-closures))
  (release
-  (flags (:standard -bin-annot -w -22))
+  (flags (:standard -bin-annot -w -22 -warn-error -A))
   (ocamlopt_flags -O3 -unbox-closures))
 )