diff --git a/opam/opam b/opam/opam
index 59c2ae9d96fd32559d40d8682e91ef386647a684..785568e6bf38127b75a0f26571601efe84363db3 100644
--- a/opam/opam
+++ b/opam/opam
@@ -100,7 +100,7 @@ depends: [
   ( "alt-ergo-free" | "alt-ergo" )
   "conf-graphviz" { post }
   "yojson"
-  "why3" { >= "1.2.0" }
+  "why3" { >= "1.3.1" }
 ]
 
 depopts: [