diff --git a/pkgs/development/ocaml-modules/base64/default.nix b/pkgs/development/ocaml-modules/base64/default.nix
index db1a4e85646..be8dabf7f60 100644
--- a/pkgs/development/ocaml-modules/base64/default.nix
+++ b/pkgs/development/ocaml-modules/base64/default.nix
@@ -2,13 +2,14 @@
 
 buildDunePackage rec {
   pname = "base64";
-  version = "3.5.0";
+  version = "3.5.1";
 
   minimalOCamlVersion = "4.03";
+  duneVersion = "3";
 
   src = fetchurl {
-    url = "https://github.com/mirage/ocaml-base64/releases/download/v${version}/base64-v${version}.tbz";
-    sha256 = "sha256-WJ3pwAV46/54QZismBjTWGxHSyMWts0+HEbMsfYq46Q=";
+    url = "https://github.com/mirage/ocaml-base64/releases/download/v${version}/base64-${version}.tbz";
+    hash = "sha256-2P7apZvRL+rnrMCLWSjdR4qsUj9MqNJARw0lAGUcZe0=";
   };
 
   nativeBuildInputs = [ findlib ];
diff --git a/pkgs/development/ocaml-modules/bistro/default.nix b/pkgs/development/ocaml-modules/bistro/default.nix
index 43cbd33f738..192bb470a66 100644
--- a/pkgs/development/ocaml-modules/bistro/default.nix
+++ b/pkgs/development/ocaml-modules/bistro/default.nix
@@ -20,7 +20,7 @@ buildDunePackage rec {
   pname = "bistro";
   version = "unstable-2022-05-07";
 
-  useDune2 = true;
+  duneVersion = "3";
 
   src = fetchFromGitHub {
     owner = "pveber";
diff --git a/pkgs/development/ocaml-modules/emile/default.nix b/pkgs/development/ocaml-modules/emile/default.nix
index f1c61ce27e8..44764033d6a 100644
--- a/pkgs/development/ocaml-modules/emile/default.nix
+++ b/pkgs/development/ocaml-modules/emile/default.nix
@@ -15,11 +15,12 @@ buildDunePackage rec {
   pname = "emile";
   version = "1.1";
 
-  useDune2 = true;
+  minimalOCamlVersion = "4.08";
+  duneVersion = "3";
 
   src = fetchurl {
     url = "https://github.com/dinosaure/emile/releases/download/v${version}/emile-v${version}.tbz";
-    sha256 = "0r1141makr0b900aby1gn0fccjv1qcqgyxib3bzq8fxmjqwjan8p";
+    hash = "sha256:0r1141makr0b900aby1gn0fccjv1qcqgyxib3bzq8fxmjqwjan8p";
   };
 
   buildInputs = [ cmdliner ];
@@ -32,10 +33,7 @@ buildDunePackage rec {
     uutf
   ];
 
-  # technically emile is available for ocaml >= 4.03, but alcotest
-  # and angstrom (fmt) are only available for >= 4.08. Disabling
-  # tests for < 4.08 at least improves the error message
-  doCheck = lib.versionAtLeast ocaml.version "4.08";
+  doCheck = true;
   checkInputs = [ alcotest ];
 
   meta = with lib; {
diff --git a/pkgs/development/ocaml-modules/h2/default.nix b/pkgs/development/ocaml-modules/h2/default.nix
index 95272890e15..1a8d0c5d639 100644
--- a/pkgs/development/ocaml-modules/h2/default.nix
+++ b/pkgs/development/ocaml-modules/h2/default.nix
@@ -30,6 +30,7 @@ buildDunePackage rec {
     src
     ;
 
+  duneVersion = "3";
   minimalOCamlVersion = "4.06";
 
   propagatedBuildInputs = [
diff --git a/pkgs/development/ocaml-modules/index/default.nix b/pkgs/development/ocaml-modules/index/default.nix
index 04373cbcce8..ebc05078755 100644
--- a/pkgs/development/ocaml-modules/index/default.nix
+++ b/pkgs/development/ocaml-modules/index/default.nix
@@ -10,10 +10,11 @@ buildDunePackage rec {
 
   src = fetchurl {
     url = "https://github.com/mirage/index/releases/download/${version}/index-${version}.tbz";
-    sha256 = "sha256-rPwNzqkWqDak2mDTDIBqIvachY1vfOIzFmwaXjZea+4=";
+    hash = "sha256-rPwNzqkWqDak2mDTDIBqIvachY1vfOIzFmwaXjZea+4=";
   };
 
   minimalOCamlVersion = "4.08";
+  duneVersion = "3";
 
   buildInputs = [
     stdlib-shims
diff --git a/pkgs/development/ocaml-modules/otr/default.nix b/pkgs/development/ocaml-modules/otr/default.nix
index d2ed78d51b8..108f4b79d78 100644
--- a/pkgs/development/ocaml-modules/otr/default.nix
+++ b/pkgs/development/ocaml-modules/otr/default.nix
@@ -6,14 +6,14 @@ buildDunePackage rec {
   pname = "otr";
   version = "0.3.10";
 
-  minimumOCamlVersion = "4.08";
+  minimalOCamlVersion = "4.08";
 
   src = fetchurl {
     url = "https://github.com/hannesm/ocaml-otr/releases/download/v${version}/otr-v${version}.tbz";
-    sha256 = "0dssc7p6s7z53n0mddyipjghzr8ld8bb7alaxqrx9gdpspwab1gq";
+    hash = "sha256:0dssc7p6s7z53n0mddyipjghzr8ld8bb7alaxqrx9gdpspwab1gq";
   };
 
-  useDune2 = true;
+  duneVersion = "3";
 
   propagatedBuildInputs = [ cstruct sexplib0 mirage-crypto mirage-crypto-pk
                             astring base64 ];
diff --git a/pkgs/development/ocaml-modules/progress/default.nix b/pkgs/development/ocaml-modules/progress/default.nix
index 4c00ff98465..b714cdf3371 100644
--- a/pkgs/development/ocaml-modules/progress/default.nix
+++ b/pkgs/development/ocaml-modules/progress/default.nix
@@ -7,7 +7,7 @@ buildDunePackage rec {
   pname = "progress";
 
   minimalOCamlVersion = "4.08";
-  useDune2 = true;
+  duneVersion = "3";
 
   inherit (terminal) version src;
 
diff --git a/pkgs/development/ocaml-modules/repr/default.nix b/pkgs/development/ocaml-modules/repr/default.nix
index f5a11919c5d..47c19154689 100644
--- a/pkgs/development/ocaml-modules/repr/default.nix
+++ b/pkgs/development/ocaml-modules/repr/default.nix
@@ -8,10 +8,11 @@ buildDunePackage rec {
     owner = "mirage";
     repo = "repr";
     rev = version;
-    sha256 = "sha256-jF8KmaG07CT26O/1ANc6s1yHFJqhXDtd0jgTA04tIgw=";
+    hash = "sha256-jF8KmaG07CT26O/1ANc6s1yHFJqhXDtd0jgTA04tIgw=";
   };
 
   minimalOCamlVersion = "4.08";
+  duneVersion = "3";
   strictDeps = true;
 
   propagatedBuildInputs = [
diff --git a/pkgs/development/ocaml-modules/repr/ppx.nix b/pkgs/development/ocaml-modules/repr/ppx.nix
index 1eb76256362..b1091114ce2 100644
--- a/pkgs/development/ocaml-modules/repr/ppx.nix
+++ b/pkgs/development/ocaml-modules/repr/ppx.nix
@@ -4,6 +4,7 @@ buildDunePackage {
   pname = "ppx_repr";
 
   inherit (repr) src version strictDeps;
+  duneVersion = "3";
 
   propagatedBuildInputs = [
     ppx_deriving