diff --git a/shell.nix b/shell.nix
index 45f1ad0..bd90833 100644
--- a/shell.nix
+++ b/shell.nix
@@ -46,4 +46,6 @@ pkgs.mkShell {
   ] ++ (builtins.map (p: callPackage p { }) [
     (sources.disko + "/package.nix")
   ]);
+
+  allowSubstitutes = false;
 }