diff --git a/pkgs/applications/science/logic/alt-ergo/default.nix b/pkgs/applications/science/logic/alt-ergo/default.nix
index 7077d56f8069..75288b5ff80b 100644
--- a/pkgs/applications/science/logic/alt-ergo/default.nix
+++ b/pkgs/applications/science/logic/alt-ergo/default.nix
@@ -9,8 +9,8 @@ let
   src = fetchFromGitHub {
     owner = "OCamlPro";
     repo = pname;
-    rev = version;
-    sha256 = "sha256-8pJ/1UAbheQaLFs5Uubmmf5D0oFJiPxF6e2WTZgRyAc=";
+    rev = "refs/tags/${version}";
+    hash = "sha256-8pJ/1UAbheQaLFs5Uubmmf5D0oFJiPxF6e2WTZgRyAc=";
   };
 in
 
diff --git a/pkgs/development/ocaml-modules/psmt2-frontend/default.nix b/pkgs/development/ocaml-modules/psmt2-frontend/default.nix
index 41e13f21a412..1cb14f75faa8 100644
--- a/pkgs/development/ocaml-modules/psmt2-frontend/default.nix
+++ b/pkgs/development/ocaml-modules/psmt2-frontend/default.nix
@@ -8,12 +8,10 @@ buildDunePackage rec {
     owner = "ACoquereau";
     repo = pname;
     rev = version;
-    sha256 = "sha256-cYY9x7QZjH7pdJyHMqfMXgHZ3/zJLp/6ntY6OSIo6Vs=";
+    hash = "sha256-cYY9x7QZjH7pdJyHMqfMXgHZ3/zJLp/6ntY6OSIo6Vs=";
   };
 
-  useDune2 = true;
-
-  minimumOCamlVersion = "4.03";
+  minimalOCamlVersion = "4.03";
 
   strictDeps = true;