diff --git a/opam b/opam
index 2087a57b17d9e994e17c68696a8d2fefb11d716b..765ae370970933c6c7e81ee64319623266223495 100644
--- a/opam
+++ b/opam
@@ -123,13 +123,14 @@ depends: [
   "ocamlfind" # needed beyond build stage, used by -load-module
   "ocamlgraph" { >= "1.8.8" }
   "why3" { >= "1.6.0" }
+  "yaml" { >= "3.0.0" }
   "yojson" {>= "1.6.0" & (>= "2.0.1" | !with-test)}
   "zarith" { >= "1.5" }
 
   # PPXs
   "ppx_deriving"
   "ppx_deriving_yojson"
-  "ppx_deriving_yaml"
+  "ppx_deriving_yaml" { >= "0.2.0" }
   "ppx_import"
 
   # GTK3 for non-macos only