diff --git a/pkgs/development/ocaml-modules/janestreet/0.14.nix b/pkgs/development/ocaml-modules/janestreet/0.14.nix
index 075f7c1f57d6..ec79317e565b 100644
--- a/pkgs/development/ocaml-modules/janestreet/0.14.nix
+++ b/pkgs/development/ocaml-modules/janestreet/0.14.nix
@@ -871,6 +871,7 @@ with self;
 
   vcaml = janePackage {
     pname = "vcaml";
+    duneVersion = "3";
     hash = "0ykwrn8bvwx26ad4wb36jw9xnlwsdpnnx88396laxvcfimrp13qs";
     meta.description = "OCaml bindings for the Neovim API";
     propagatedBuildInputs = [ angstrom-async async_extra faraday ];
diff --git a/pkgs/development/ocaml-modules/janestreet/0.15.nix b/pkgs/development/ocaml-modules/janestreet/0.15.nix
index 934f7d308592..59f146542e12 100644
--- a/pkgs/development/ocaml-modules/janestreet/0.15.nix
+++ b/pkgs/development/ocaml-modules/janestreet/0.15.nix
@@ -1063,6 +1063,7 @@ with self;
   };
 
   vcaml = janePackage {
+    duneVersion = "3";
     pname = "vcaml";
     hash = "12fd29x9dgf4f14xrx7z4y1bm1wbfynrs3jismjbiqnckfpbqrib";
     meta.description = "OCaml bindings for the Neovim API";