diff --git a/machines/compute01/ds-fr/default.nix b/machines/compute01/ds-fr/default.nix
index c8f3b4e..38eb9be 100644
--- a/machines/compute01/ds-fr/default.nix
+++ b/machines/compute01/ds-fr/default.nix
@@ -25,7 +25,12 @@ in
         (old: {
           dsModules = old.dsModules.overrideAttrs {
             prePatch = ''
-              ${pkgs.lib.getExe pkgs.git} apply -p1 < ${builtins.fetchurl "https://git.dgnum.eu/DGNum/demarches-normaliennes/commit/${dgn-id}.patch"}
+              ${pkgs.lib.getExe pkgs.git} apply -p1 < ${
+                pkgs.fetchurl {
+                  url = "https://git.dgnum.eu/DGNum/demarches-normaliennes/commit/${dgn-id}.patch";
+                  hash = "sha256-aCq/WkV4+PUSIzXgznwm2sAcaz12Y1zmUbh7QoXoMsM=";
+                }
+              }
             '';
           };
         });