diff --git a/pkgs/development/python-modules/firedrake/default.nix b/pkgs/development/python-modules/firedrake/default.nix
index b223e632552c..63977170c065 100644
--- a/pkgs/development/python-modules/firedrake/default.nix
+++ b/pkgs/development/python-modules/firedrake/default.nix
@@ -57,14 +57,14 @@ let
 in
 buildPythonPackage rec {
   pname = "firedrake";
-  version = "2025.4.2";
+  version = "20250331.0";
   pyproject = true;
 
   src = fetchFromGitHub {
     owner = "firedrakeproject";
     repo = "firedrake";
-    tag = version;
-    hash = "sha256-bAGmXoHPAdMYJMMQYVq98LYro1Vd+o9pfvXC3BsQUf0=";
+    tag = "Firedrake_${version}";
+    hash = "sha256-J0oAZWkzcrgbry5OTG8hKrIgHcwJtzaDw8staOLM9u4=";
   };
 
   postPatch =